I know European powers sent observers to take note of the goings-on during the American Civil War.
My question is why The Allies (mainly France) leading up to the war did not foresee widespread use of then modern combat tactics like trench warfare, wire obstacles and heavy machine guns? All three were used in The American Civil War and The Ruso-Japanese War. Granted even the Central Powers probably couldn’t comprehend the how deadly the combination of all 3 and much more would be.
There is a previous answer dealing with this topic [here] (https://www.reddit.com/r/AskHistorians/comments/34w68v/did_any_of_the_world_war_one_commanders_study_the/cqyokv2/?st=k1r5gx7c&sh=f810f8fa) by /u/DuxBelisarius and /u/elos_
That answer touches on pretty much every major aspect that could be learned from the American Civil War, and how those lessons were learned mainly through other conflicts, and also newer ones. /u/DuxBelisarius also hinted at in one of his follow-up towards the one major gap in his answer: Cavalry! I’ll be discussing British Cavalry in this answer.
Cavalry have had a bad rap in the public consciousness regarding the First World War, and in fact many conflicts. The Cavalry is often seen as an aristocratic and out of touch branch of service that only held back the future and modernization. Much of this is polemics. Cavalry, like other arms, had a place on the Battlefield even through the World Wars! And prior to the First World War the American Civil War provided a great look for European Leaders for the evolution of the Cavalry.
The debates around Cavalry during the 1890s and 1900s centered around the Arme Blanche, that is, whether or not should utilize close quarters weapons and charges. Opponents, especially in this early period, favored a more mounted infantry role where the weapon of the cavalryman was a carbine or rifle. Proponents of the Arme Blanche weren’t advocating only for close quarters weapons, but rather that Cavalrymen should operate as a sort of “hybrid” where they could act as mounted infantry and use their rifles, but when the situation presented itself, they would also be able to drive home a charge. This in addition to the other roles Cavalry fulfilled such as scouts.
This “hybrid model” was the basis of Union Cavalry during the American Civil War, and it is through the American Civil War that men such as Douglas Haig, who were in favor of the “Hybrid” model drew some of their initial conclusions. Haig argued in 1892 that "cavalry that cannot fight on foot is not up to the requirements of the present day”. In 1907 in his Cavalry Studies: Strategical and Tactical, Haig contrasted the successes of the Union Cavalry with the failures of the Prussian Cavalry during the Franco-Prussian War.
The Second Boer War, starting in in 1899, helped vindicate the usefulness of the Arme Blanche (and Hybrid trooper) in the eyes of its supporters. Cavalry was demonstrated to have been able, through the nature of its mobility, to ride through fire-zones and beat back a force of Boers while remaining relatively unscathed. The Cavalry’s mobility, for example, allowed it to engage a force of Boers at Paardeberg and hold the line, so to speak, until the Infantry arrived. At Zand River, just the threat of a charge (as British horses were worn down) was enough to cause a Boer retreat. The Boer War opened up another chapter of the Arme Blance controversy, but it provided its supporters with much ammunition that the “Hybrid” style of Cavalry seen during the American Civil War could and would work on a modern Battlefield.
Cavalry of course was not fighting alone and Cavalry Brigades were augmented with both Machine-Guns and Horse-Artillery. This additional firepower meant that Cavalry Brigades, which had less men than an Infantry Brigade, had a larger amount of firepower.
The Western Front of the First World War proved supporters of the “Hybrid” Cavalry correct. Cavalry units, through all four years of the war, were able to leverage both their mobility and firepower to capture and hold positions, as well as successfully charge the Germans. The Secunderabad Brigade, for example, charged on July 14th 1916 near High Wood. They were screened by their artillery and MGs and suffered about 8 killed that day, and 50 wounded. Its other strength was mobility, such as at Monchy le Preux, where Cavalry was able to reinforce a badly mauled infantry force. Utilizing their firepower in machine-guns and artillery, the village was held by the Cavalry (albeit a great cost as German artillery rained fire down and orders were not passed down to move the horses out of the village).
None the less, the First World War represented, for the Cavalry, vindication of the lessons learned regarding “Hybrid” cavalry troopers during the American Civil War.
Sources and Recommended Reading