Everyone has heard the conventional wisdom, that metal armour became obsolete, as guns improved. It should be fundamentally correct, but I am interested in understanding the process in more detail, especially key moments/battles.

Wikipedia gives the impression that metal armour did go away very slowly and part by part.

Back and breast plates continued to be used throughout the entire period of the 18th century and through Napoleonic times, in many European (heavy) cavalry units, until the early 20th century.

Further on:

At the start of World War I, thousands of the French Cuirassiers rode out to engage the German Cavalry.[...] Their armour was meant to protect only against sabres and light lances. The cavalry had to beware of high velocity rifles and machine guns, unlike the foot soldiers, who at least had a trench to protect them.

Still, even given gradual replacement, there should be experiences and deliberations that drove the replacement. Does anyone know specific battles that contributed to discarding elements of armour? Even some arguments between generals who argued pro and contra? We know that armour from light materials is still around.

Using the example of Lars Bosteen in the comments:

I am looking for cases where (for example), after a battle, a country's military assessed what happened and decided 'those cuirasses/helmets/greaves didn't do any good, let's not use them anymore

  • Comments are not for extended discussion; this conversation has been moved to chat. – Mark C. Wallace Oct 20 '19 at 12:45
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    On that basis, I'll vote to reopen as I think answers could produce some interesting primary source evidence...if it exists. – Lars Bosteen Oct 20 '19 at 13:37
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    I think this question is worth re-open; I think that it could stand a bit more tweaking/revision - I'm not sure that what the question asks represents _what @Ludi wants to know. It almost seems like you're asking "What is the process/evidence/ that countries used to justify abandoning armor?" The current phrasing focuses attention on tactical details, but the intent of the question seems to be about strategy/investments. I think the key is somewhere between the two - what information from tactical results were used to justify strategic investments? – Mark C. Wallace Oct 21 '19 at 17:52
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    @MarkC.Wallace I am not sure I sufficiently understand the distinction and its significance, but your last sentence seems to be what I want. If my gut feeling is correct, the gradual abandonment of m. armour should not have taken place without „experimental“(~tactical?) results and deliberations. Even if costs were certainly considered, what to replace and what not should have been decided on experimental grounds. If we isolate interesting candidate battles from shreds of sources, it is a matter of diligence to find more fascinating sources :) – Ludi Oct 22 '19 at 18:07

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