And surely yes, if I were local peasant near battlefield I would go and pick through it after everyone is gone. Or at latest when most of the stink is gone... Metals at least had value.
The Gruesome History of Eating Corpses as Medicine
https://www.smithsonianmag.com/history/the-gruesome-history-...
Likely, but it seems they aren’t 100% sure of that at the Encyclopædia Brittanica. https://www.britannica.com/list/7-surprising-uses-for-mummie...:
“It was claimed by author Mark Twain that mummies had been used as fuel for locomotives. In his 1869 travel book called The Innocents Abroad, Twain describes the first railroad in Egypt. Because of the lack of trees and the price of coal, Twain claims that the Egyptians used mummies instead. He wrote, “[The fuel used] for the locomotive is composed of mummies three thousand years old, purchased by the ton or by the graveyard for that purpose.””
Also, FTA: “we know the British imported mummies and bones from Egypt on an industrial scale”
Just have a look at https://en.wikipedia.org/wiki/List_of_museums_with_Egyptian_... to get an rough idea of the extent of Egypt-mania in Britain; the 'UK' section dwarfs the others! So although that quote is rather vague, I strongly suspect that it is simply referring to the large quantity of Egyptian artefacts that were being excavated and moved to museums in Britain, especially after Epypt was annexed by and amalgamated into the British Empire in 1882.
https://short-history.com/cats-caused-the-ancient-egyptians-...