I posted the following on the Yahoo 1870 group earlier this week;
'The proofing of the cuirasses of French cuirassiers under the Second Empire is described by Louis Delpérier in the 1981 special issue on the cuirassiers of the French magazine "Uniformes". On page 7, Delpérier writes " Only the breastplate was proofed. Out of a group of 100, twenty sub-groups of 5 each were organised by order of weight. The lightest breastplates of the first sub-group were each subjected to the impact of three bullets fired at the middle of the breastplate from a distance of 40 metres. The group would only be accepted if the first three withstood this: it was required that the breastplate was not pierced by any of the three bullets, and that no more than one of them tore it." (my translation).
Unfortunately, Delpérier does not say for how long this practice continued. In spite of the footnote to Bonie that you quote, French cuirassiers went to war in 1914 still wearing the cuirasse. Had their cuirasses been proofed?
We should not be too francocentric in thinking about this question. Prussian cuirassiers also wore the cuirass in action in 1870. It would be of interest to know what were their proofing requirements, if any."
Thanks to Nashville, we now know that the Prussians proofed their cuirasses too. Does anyone have any more information?
NB The eagle helmet crest would not have been worn on active service, but would have been replaced by a plain spike.
Charles