Cavalry became an outdated way of war that quickly went away after early World War I cavalry charges against machine gun nests.

This is a historical claim, judged against the established military-history record. The claim is that after early WWI charges against machine guns, mounted cavalry became obsolete and 'quickly went away'. True: historians agree that mounted cavalry stopped being a significant arm of war within a short time of 1914–15, meaning within a few years, with no major later use in combat. Mostly true: cavalry became obsolete in its main role on the Western Front soon after 1914, but there was minor, marginal later use that the claim glosses over. Mixed: cavalry's obsolescence did begin with WWI, but it stayed in substantial use for a decade or more. False: the record shows cavalry was not made obsolete by WWI. Mostly false: the record shows mounted cavalry kept a significant combat role for decades. Examples would be large cavalry formations in the Middle East campaigns of WWI, the Russian Civil War, the 1920 Polish–Soviet War, or Soviet and other cavalry corps in WWII. In that case the obsolescence is real but 'quickly went away' overstates it.

Set before the research began.

1. E1 Cavalry - Wikipedia Wikipedia

   “Once the front lines stabilised on the Western Front with the start of Trench Warfare, a combination of barbed wire, uneven muddy terrain, machine guns and rapid fire rifles proved deadly to horse mounted troops and by early 1915 most cavalry units were no longer seeing front line action.”

2. E2 The use of cavalry in the First World War - Hodder Education Magazines Hodder Education (Hachette Learning) · 1 September 2012

   “However, the assertion that military advances in the run up to the First World War made cavalry a redundant force has been challenged by the evidence, which shows that there were still occasions, even in 1918, when they were used.”

3. E3 Cavalry - Wikipedia Wikipedia

   “The 1920s saw an interim period during which cavalry remained as a conspicuous element of all major armies, though much less so than prior to 1914.”

4. E4 Cavalry - Wikipedia Wikipedia

   “Mounted Soviet forces also played a role in the encirclement of Berlin, with some Cossack cavalry units reaching the Reichstag in April 1945.”

E1 supports a fast decline on the Western Front: by early 1915 most cavalry units there were no longer seeing front-line action. However, E2 says cavalry was still used as late as 1918. E3 says cavalry remained a conspicuous element of all major armies in the 1920s, though much less so than before 1914, and E4 records Soviet mounted forces, including Cossack cavalry units, playing a role in the encirclement of Berlin in 1945. Cavalry's obsolescence is real, but its use in 1918 [E2], its reduced but conspicuous presence in major armies in the 1920s [E3], and its role in the 1945 encirclement of Berlin [E4] cut against "quickly went away".