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.
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