I made the following post some time ago, perhaps it will be of some use to you. Although it deals mostly with the Czechoslovak border fortifications, these did play a key part in the defense plans for a war against Germany. I have expanded on the general plans for war in a post below.

The popular history claim is that Czechoslovakia had heavily fortified its border with Germany, however, the facts tell a different story. There certainly were plans for rather massive border defenses and indeed some of those had been built by the time of the Munich crisis, but the construction was nowhere near finished in several places – or even started for that matter – and the Czechoslovak staff actually expected losing territory to the German advance from the west and a fighting withdrawal eastwards.

The Czechoslovak government decided to build a series of border fortifications in the 1930s, with the Maginot line being an obvious inspiration. In autumn 1934, a couple of months after the first funds were earmarked for the construction, a Czechoslovak delegation visited France, and in early 1935 French advisors arrived in Prague.

Realizing the exceedingly difficult scenario an ever more likely war with Germany would present, the military plans called for fortifications in the north to cover a fighting withdrawal to Moravia and Slovakia where the Czechoslovak forces would wait for a French counterattack.

In 1936 the government decided to build two lines of heavy forts in basically all viable approaches from Germany. Much of the border is mountainous, forested and difficult to cross, and remember that this is still before the 1938 Anschluss of Austria, limiting the shared border to the north and west of Czechoslovakia.

However, the plan had to be rejected due to outrageous projected costs and a building time of at least six years. A decision to limit the defenses to just a single line was taken, but even this was later deemed unfeasible. The idea of heavy defenses at all the key parts of the border was abandoned or rather modified yet again in 1937, and these were to be built only in selected areas mostly in the north of the country.

This new plan instead called for over fifteen thousand lighter structures and pillboxes with overlapping fields of fire spread fairly deep along the border – the "Light fortification, Mk. 37" also known as "řopík" (after "ŘOP", the acronym for the government agency responsible for these works), a concrete bunker usually armed with machine guns and housing roughly between a couple of men to a squad. In addition, tank traps, barbed wire and minefields were also to be deployed.

In total, 1276 pieces of heavy fortifications and 15 463 of the lighter ones were to be built over a period of ten years to spread the still exceedingly high costs.

Herein lies the problem: Before the German occupation, the construction of only 263 heavy bunkers was finished, and during the time of the Munich crisis, only a small number (near Bratislava and in the northeast of what is now the Czech Republic) were in a state of war readiness and adequately equipped. Light fortifications were about two thirds complete with some ten thousand pillboxes ready. Furthermore, this was only after the annexation of Austria, extending the German-Czechoslovak border significantly and to regions with only light defenses.

The fortification system also had several weaknesses. It lacked any active anti-aircraft defenses, something only exacerbated by the general inferiority of Czechoslovak air force to its German counterpart. Anti tank combat was also a concern, as several bunker variants had only limited fields of view for their guns, and the number of anti tank assets was generally low, with heavy mines not available in any significant numbers. One solution to this problem would be the use of heavy fire support bunkers, but not a single one of those was armed before Munich. Inadequate troop training for operating in fortifications, and the possibility of a rear attack either by paratroopers or local Germans also were causes for concern.

With the German forces threatening the lightly defended south, and the northern and western fortifications unfinished, even a vastly different outcome of Munich would see Czechoslovakia in a very difficult position.