This is a really fascinating question, and I’m not sure how far I’ll be able to do justice to it. My interest here is much more in the history of opposition to fascism – that is, why do efforts to oppose the rise of fascism succeed or fail in interwar Europe. The question you’ve asked has obvious relevance to this broader issue – basically, did the German Communist Party’s (KPD) tactics prior to 1933 condemn German resistance to Nazism? Why didn’t German communists seek to cooperate with other enemies of the Nazi Party, instead of focusing their political attacks on potential allies like Social Democrats? On one level, this is an impossible historical ‘what if?’ – we can’t know whether a more unified German left would have forestalled the rise of Hitler. But we can seek to understand and explain why things happened the way they did.

Recent German, and to a lesser extent Italian, history offers some of the explanation. In both countries, revolutionary unrest was put down by paramilitary forces, often composed of demobilised veterans of the war. In Italy, of course, these were the beginnings of the Fascist Party itself, which established itself across much of Italy (particularly the north) by crushing socialist strikes and occupations when local authorities were unwilling or unable to, to the delight of local business owners and the Italian middle class. The success of Italian fascism, therefore, depending on the ability to violently disrupt and demoralise the organised left. In Germany, a similar role was played by Freikorps, paramilitary groups made up predominantly of military veterans who flourished in aftermath of Germany’s defeat. Most famously in the case of the Spartacist Uprising in January 1919, they were used by the government to help crush revolutionary unrest, including by murdering key leaders like Rosa Luxemburg and Karl Liebknecht.

In Germany, however, there was a unique twist: it was a Socialist Party (SPD) chancellor, Friedrich Ebert who gave the order to bring in the Freikorps to Berlin, and was held responsible for the violence. In Germany, the SPD aligned itself within a so-called ‘coalition of order’ in Weimar Germany, made up of the political groupings whose priority was ensuring social stability and discipline against the revolutionary threat of the far left and, to a lesser extent, the far right. The SPD, therefore, was an active participant in proposing and passing measures that attacked the KPD throughout the 1920s, in terms of restrictive legislation, but also as the political leaders who led (often violent) national or regional responses to communist-backed strikes and demonstrations. In other words, from the KPD’s perspective, the SPD had proven that it preferred to uphold the capitalistic status quo rather than throw its lot in with a socialist revolution, showing where its true loyalties lay.

The lesson learned by anti-fascists in the 1920s was simple: the far right is violent, and if unopposed will not hesitate to crush the left, with the tacit or open approval of the state. As such, the KPD in particular provided a key source of grassroots resistance to Nazi violence directed against working-class communities through organisations like the Roter Frontkämpferbund. This paramilitary-style group, with local chapters in many German cities and towns, sought to confront and defend against fascist violence directly, as well as defending communist rallies from disruption by police and Nazis alike. They were often successful on a tactical level in defending themselves, as well as more aggressively taking the fight to the Nazis directly on occasion. But though it prevented the piecemeal destruction of the German left, as had been the case in Italy, it was also not a winning strategy.

For one, the situation was made worse by the Great Depression. It now genuinely appeared as if capitalism was experiencing its long-prophesised final crisis, and the hour for revolution was drawing close. This made assembling the most powerful revolutionary party possible the main goal – and this meant competing for socialist working-class support on the left. This was the strategy employed by Communist Parties across the world (orchestrated by the Communist International in Moscow, in which the KPD was very influential), but it was in Germany where it found the most enthusiastic support among communists, who were already predisposed to seeing the SPD as their main enemy. This helped further radicalise the KPD – their increasing reliance on the unemployed for support, for instance, diminished their influence in the workplace and led to them conducting their politics on the streets, invoking spectacle and violence as their key form of political engagement. Yet this ignored a key plank of Nazi success. While fascist success is dependent on violence, and being seen to offer radical violent (either implicitly or explicitly) solutions to societal problems, it also rests on victimhood. The Nazis campaigned on the basis that German society was collapsing, with traditional elites no longer able to contain the revolutionary chaos caused by Bolshevism. Only the Nazis, with their willingness to take the required firm measures to restore order, were able to offer a solution to these problems. This meant that every time the Nazis were on the receiving end of violence at the hands of communist-backed paramilitaries, they could use this to reinforce this message: Germany is now ungovernable, unless you put us in charge. It’s worth remembering that the KPD was the other major beneficiary of the post-1929 crisis: as the communists gained strength, more and more non-communists started to buy the Nazi message that only they could contain the rising tide of revolutionary chaos.

In the aftermath of the Nazi rise to power, and their successful suppression of communists and socialists alike, it was clear that the KPD’s strategy had been flawed. Fascism, it was clear, could not be allowed to gain power and get the chance to turn the resources of the state towards suppressing its political enemies. This realisation led to a conception of anti-fascism not simply as opposition or resistance to fascist organisations, but as a unifying ideology. Communists around the world reversed their policies entirely: no longer were socialists and other leftist enemies to be condemned as ‘social fascist’ enemies, they were now vital allies in a united front against fascism. Efforts to build such anti-fascist alliances saw mixed success over the rest of the decade, as I discuss in this older post, but laid some of the groundwork for effective domestic and international resistance to further fascist expansion, both in specific contexts but also in building a wider political consensus that eventually saw an anti-fascist coalition ranging from communists to Churchill fight and win the Second World War.

This strategic ‘turn’, which took place over the course of 1934-5, is generally known as the ‘Popular Front’, which was embraced enthusiastically and successfully by many Communist Parties around the world. It’s worth noting though – particularly in light of your question about whether German communists regretted their tactics – that the KPD were among the last to accept this shift, and implemented it only reluctantly and ineffectively. After the end of the Second World War – and a shift back to the rhetoric of ‘social fascism’ and viewing social democracy as the key enemy following the founding of the ‘Cominform’ in 1947, German communists happily returned to the language and attitudes of the 1920s. It’s worth noting, of course, that many of the politicians who ran the East German state for its entire existence had come of age in the KPD under Weimar in the 1920s, and its politics of confrontation and intransigence became something to be nostalgically valorised rather than condemned.

Edit 1: Typos. Gah.

Edit 2: Take the time to read further down for a great comment from the perspective of the international communist movement and its responses to fascism from u/NiftyJasmine

Edit 3: Thank you kind, silvery redditor!

Okay, so I can provide some context on the international communist crusade against social democracy or 'social fascism' which may give some illumination regarding the German situation. I may also be able to specifically reference the KPD.

​

So, the first thing to understand about national communist parties in the interwar period is that there has been and continues to be major debate amongst historians regarding the level of autonomy that communist parties had from the Communist International (Comintern) in terms of both the official party line and the day-to-day activities of these parties on the ground. The favourite theory since the opening of the Soviet archives in the 1990s ‘rejects the view that Communists were marionettes being manipulated by a Kremlin puppet-master’, but also argues that ‘it is equally unrealistic to see Communists as acting totally within the context of their own labour movements, utterly unaffected by the Comintern’. [1]

​

With that in mind then, the Comintern was concerned by the growth of fascism from the beginning of the 1920s when Mussolini took power in Italy; however, communist theoreticians struggled to define 'fascism' throughout the interwar period, which was certainly an issue among national parties too. A the Fourth World Congress of the Comintern held in 1922, fascism was presented in the speeches of different cadres as the ‘political enemy of the capitalist bourgeoisie’, the ‘political offensive of the bourgeoisie against the working class’, and as having ‘battalions composed of workers, rural proletarians and part of the peasantry’. [2] This confusion among communist intellectuals was still an issue with the rise of fascism in Germany in the 1930s.

​

In addition, some communist theoreticians until 1935 viewed fascism as a shallow movement with little in the way of actual policies. Klara Zetkin, the veteran German communist warned her fellow comrades of the dangers of 'viewing fascism only as a military-terrorist movement and not as a mass movement with deep social roots.'[3] Despite this, even Zetkin was unconvinced by the staying power of fascism; she believed that Italian fascism would collapse as it would be ‘unable to keep together the forces which helped it to get into power’ and that ‘the workers will very soon come back to their class interest and class duty’ by rejecting fascism and embracing communism. [4]

​

As you mentioned in your question, there was a hope that fascism would lead to a communist revolution, but this seems to have been because communist intellectuals believed that fascism was indicative of the breakdown of capitalist society, and as such they didn't need to mount an active defence against it. Communist internationalists believed that fascism was 'one of the classic forms of counter-revolution in the epoch where capitalist society is dying’. [5] Amadeo Bordiga, an Italian leader in the Comintern, believed that fascism did not contribute ‘to the traditional ideology and programme of bourgeois politics’ and was ‘full of difficulties that it is unable to overcome’. [6]

​

With regards the question of social democracy, the rise of Italian fascism may be the key to understanding the communist crusade against it in the Comintern's Second Period. The conditions that allowed Mussolini to take power in Italy were seen by the communists as being compounded by the fact that the Partito Socialista Italiano (PSI) refused to participate in a potential communist revolution in the country after World War One. Towards the end of the 1920s, the Comintern expressed concern about the real or imagined threat of 'social fascism', or social democracy. The Kommunistische Partei Deutschlands claimed that ‘Social Fascism is Socialism in word, Fascism in deed’, while fascism and social democracy were presented as ‘the two sides of the same instrument of capitalist dictatorship’, with social democrats unable to 'be a reliable ally of the fighting proletariat'. [7] The goal of this campaign against social democracy was to isolate and destroy 'social democracy as a force moving the working class towards fascism’, but it actually had the opposite effect; the communists were often left isolated during the period. [8] In addition, the claims made by communists that social democracy and fascism were the same ‘prevented arrival at an analysis of the fascist phenomenon and its peculiar traits’, with the consequence that communists were underequipped to effectively tackle it when Nazism became a real threat.[9] In addition, this ultra-left turn in Comintern policy actually affected membership numbers. Andreas Wirsching has argued that conditions in Germany ‘offered incomparably clearer ideological and propagandist points of contact for the thesis of ‘social fascism’ than in France’. Between 1929 and 1932, the number of KPD members rose from 98,527 to 252,000’, while in France, which was far more syndicalist than its German neighbour, there was a drop from 52,372 members in 1928 to 28,825 in 1933. [10]

​

In fact, it wasn't really until the Popular Front policy was adopted by the Comintern in 1935 that communist parties began to make moves towards collaboration with other parties on the left; there were some attempts by German communist propaganda Tsar Willi Münzenberg to create communist front organisations directed against fascism from 1932 to 1934 based in France: the Comité mondial contre la guerre et le fascisme and its sister committee, the Comité mondial des femmes contre la guerre et le fascisme (my specialty!), for example. However, national communist parties themselves did not really try to organise alongside other socialist parties until the February 6 1934 riots in Paris, and even then it was only the French party making these moves, perhaps due to the syndicalist nature of French politics.

​

To answer your question regarding the hope that fascist dictatorship would lead to a 'true communist revolution' and whether this helped to create the theory of 'social fascism', I would argue that it may have had a small influence. However, I tend to favour the theory that the crusade against 'social fascism' started because the Comintern was concerned by the fact that socialist and labour parties had the potential to take away potential supporters and dispose them against communism and thus hoped to isolate social democrats and grow their own membership numbers (as worked to some extent in Germany, as we have seen).

​

I hope this helped, I got a bit caught up in the history of the international communist response to early Italian fascism, but I hope I managed to provide some context nonetheless!

Edit: formatting/references

Hi there, I specialize in the Weimar Republic.
Before I answer the question entirely however, it is best to provide some context to the development of left-wing thought in Germany in the build-up to the take over of the NS regime.
The KPD (Kommunistische Partei Deutschlands) disdain for the SPD ( Sozialdemokratische Partei Deutschlands) had its roots in the late stages of WW1 and the early stages of the Weimar Republic. In early 1918 the opportunity arose for a peace treaty to be signed under the 14 points of Woodrow Wilson. The deal would have resulted in Germany being stripped of its colonial holdings, given a fairly strict war indemnity- though not as harsh as Versailles-, and a number of other terms. The KPD, which had yet to become a German puppet for the Bolsheviks, wanted desperately to accept the terms of the treaty. This hesitance stemmed partly from their pacifism but also from their ideological understanding of the war. The KPD saw the war as a direct result of the contradictions of capitalism and was being perpetuated ad infinitum by capitalism. The KPD was, however, a fringe minority party and so they lobbied other leftist parties, the SPD in particular, to accept the conditions as well on behalf of the civilian government. The SPD, along with the rest of the civilian government and military, rejected the proposal from the Entente. In the SPD's view, the rejection of a peace proposal was much more of a matter of self-preservation than any malintent on their part. The memories of being completely outlawed were still fresh in the minds of many senior leaders, and they were hesitant to do anything that would draw the ire of the majority parties that could lead to a new outlaw. There was indeed a very valid concern for being outlawed during the war too because the ruling parties in Germany had agreed to a Burgfrieden, in which they all agreed to a political truce for the sake of the war effort. Breaking ranks would very rightly be seen as a breach of that truce, and would have dire political consequences. Therefore, the Social Democrats went along with the war and only pushed for the armistice when it became obvious that the war was lost and the army on the verge of collapse. After the armistice was signed, Germany was in political turmoil. After much maneuvering and politicking, Philip Scheidemann declared Germany a republic under the leadership of the SPD party leader, Friedrich Ebert. The KPD, on the other hand, wanted to use the anarchy to establish a communist state, much like what was being done in Russia at the time. Thus the Spartacists, an activist/paramilitary branch of the KPD, launched a revolt in January of 1919 that was quickly and brutally suppressed Freikorps paramilitaries with the support of the SPD. In the resulting confusion, Karl Liebkecht and Rosa Luxembourg, two of the leading thinkers in the KPD were gruesomely assassinated by Freikorps officers who later went practically unpunished. There were a number of other far-left insurrections launched in Germany around the same time, and all were suppressed in a violent manner. The largest insurrection, the Bavarian Socialist Republic, saw tens of thousands deployed on both sides.
In any case, the SPD's acquiescence to the continuation of the war that only benefited capitalism, and the annihilation of the communist uprisings made the SPD class traitors in the eyes of the KPD, despite whatever overtures they made to class struggle. This made any cooperation with the SPD ideologically impossible for much of the Weimar Republic. The hard feelings began to fade in the late 1920s when more pragmatically minded leadership took over. Political connections were reforged, and there was even some suggestion of being brought into a coalition. However, when Stalin took power, he convened the world's communist parties and functionally turned them into miniatures of his own brand of Bolshevism. With the "Stalinification" of the KPD complete, the German communists took all of their marching orders and their ideology from Russia. Part of this included renewing attacks on the SPD as class traitors and as capitalists, thus leading to the KPD being left out of the Einheitsfront.
Bolshevik ideology after Stalin took over was remarkably anti-Semitic, albeit for different reasons than the NS were. To the Bolsheviks, Jews were the primary beneficiaries of capitalism and its financiers and were therefore complicit in the oppression of the proletariat. As a result, it seems to be that the expressions of anti-Semitism were much more rooted in their own expressions of ideology rather than any attempt to court the NS vote. In Bolshevik understanding of Fascism, Fascism was functionally the end-stage of capitalism and thereby also end-stage fo the oppression of the working class; therefore, revolution was destined to come about one way or the other. Very little I have read suggested how exactly revolution was to come about after the NS secured their hold on power. Indeed an armed revolt was impossible since the NS forced many of the German KPD members into concentration camps or into exile in the Soviet Union, though there was some fleeting optimism for revolution.
Ironically enough, many of the German communists who had been able to make it to the Soviet Union were killed during the purges of 1937, because Stalin was paranoid that they were in fact spies sent on behalf of the NS or that they were not entirely loyal to the party as the case may be. In any case, whatever theories for how to establish communism in NS Germany likely died with them, not that they were given much weight anyway. The murdered German communists were mourned along with the so many others killed during the purges when Nikita Kruschev assumed power after the death of Stalin, but the official party stance on Judaism and its role in global capitalism changed little. Indeed to admit that the party was capable of fallibility in more than one aspect was practically fatal, given that the party touted its perfection.
If you're interested in other hybrids of Bolshevism and Fascism, you may want to look at Georg Strasser, who was a prominent member of the NS. He theorized quite a bit about using NS social policy with Communist economic policy. Functionally he was the original Nazbol before it was cool for ironic and edgy teenagers

While a lot more can be said, you may be interested in this previous thread.

The answer already given is not complete.

The book "Vorwärts und nicht vergessen" from Bernt Engelmann describing the SPD and the workers movement in Germany from the 1800s to the 1970s is a must.

One must understand the position of the orthodox Marxists: The bourgeoisie should fight against each other and not the working class, because they would become otherwise the means of the bourgeoisie. As late as 1912 there were Pan European congresses discarding the idea workers have to fight against each other because of the concept of a Nation. I didn't helped and the idea of nationalism won in 1914 in all of Europe, while the minority of leftists were strong, but a minority.

When in 1914 the SPD voted for the war budget, most opposition against the war was already excluded from the party. At this point the orthodox Marxists in the SPD were not longer a force in the party. In 1916 the Spartakusbund was founded, which became later the KPD. The emperor became at this time a constitutional monarch and the military ran the organization of the nation. The left behind working class in the cities were starving. Opposition against the war became popular, but the military was able to oppress any opposition.

When the November revolution started in the city of Kiel so called Räte overtook in parts of German the political management and the Emperor abdicated a little bit later. The template of the Räte were the Soviets, but they were partially elected by workers. Since the Räte were a collection of various political forces, the struggle was stressing the workers. The social democrat Scheidemann and the Communist Liebknecht declared at the same time a new republic. This didn't went well for the communists. The SPD collaborated with the remains of the Wehrmacht and over the whole country militias suppressed the system of Räte and many activists were killed. The communists tried to use weapons as well, but they were too weak.

1918 Germany was bankrupt. The following governments with participation of the SPD paid with printed money which caused a hyperinflation. The hyperinflation was resolved in 1923, but now money for investments was missing. Police forces were extreme conservative and active involved into oppressing public activities of the communists and it were politicians of the SPD who started this.

The 1920s was a good time for the communists, since the USSR offered cheap culture, healthcare and kindergarten in the large cities. Moscow was seen as the great template for a glorious future. A lot of intellectuals became members of the KPD (Komunistische Partei Deutschland).

German industry became a lot of loans from the US which lead to a small boom of the economy but austerity was always prevalent. When the 1928 US banks wanted the money back and the flow of money vanished 5 million became unemployed and there was almost no welfare existing. German governments which included the SPD continued with austerity . The NSDAP as well as the KPD grew stronger. In 1930 Hitler became Chancelor and his forces arrested masses of members of the KPD immediately while the leadership of SPD wanted to wait until Hitler outed himself as an idiot. It was actually a command to the simple members.

When Hitler became dictator in 1933 his forces tried to arrest immediately leading members of the SPD too. It was an irony when communists showed social democrats how to act in the underground.

After WW2 the SPD became again anti-communist under Kurt Schuhmacher. The conservatives and social democrats supported later the prohibition of the KPD by the highest court and excluded leftists from being a employee of the state (teacher, postman, etc). Former communists concentration camp prisoners lost their pension, while former members of the NSDAP continued to be employees of the state.

The leadership of the GDR was basically the part of the KPD who survived Stalin in Moscow. Most communists immigrants from Germany died because of the cleansing. They announced a merge of forces with social democrats. Kurt Schuhmacher the leader of the SPD reacted fast and prevented any discussion by command or exclusion. And so the GDR simply dictated the merger in the east.

The SPD was since the foundation in the 1860s a split party. In the beginning the SPD was almost exclusive orthodox Marxists. But when Marx made a critique on the program of Gotha the influence of union officials was visible. While parts of the party continued to read Marx until the 1970s the concepts of politics after the removal of the socialist laws in 1892, became pragmatic in the sense the SPD wanted not longer a revolution but an equal participation of the workers in politics. As a result the will of the SPD to continue simply with the Republic of Weimar without including progressive forces, the republic started quite bloody and ended in a disaster.

The leftist dream of a Pan European workers movement incl. the management of politics by workers died. Parties like the KPD continued this dream but since the votes were split between SPD and KPD and the population in the rural regions were conservative, the outlook wasn't good.

Was the SPD an active supporter of fascism? I don't think so. At least they didn't wanted it, but like all factions of the workers movement they were hierarchical organized with the demand for an unconditional following of the leadership as soon a decision was made showed consequences. Democracy started in liberal education clubs for workers in the 1830s, because education was seen at the means to make a better human. And it were these clubs later who started a huge parts of the organized workers movement. With the mindset of the early 1800s nobody can expect a sudden discontinuation of the past. Marx was in this sense much more a radical intellectual than the workers movement. It's easy to be more wise than in the 1800s and 1900s.

Update:

Thank you for the silver!

Since here was a removed question for sources. The mentioned book is one if most complete books about the workers movement in Germany and it is the one which is giving a insight into the greater picture. But Germany has a lot of specialized academic documentation about the workers movement written in the 1970s to 1990s, which can't be find elsewhere. What it makes so valuable to me, it helps to understand the mindsets and the phenomenon of the years from 1930-1945. Learning a local language for reading like Germany is paying off. There is no substitution for German in this case. Especially Stalinism and the seamless continuation of West Germany in the West is only understandable when someone is studying the mindsets of this time