Why do veterans use poppys as their symbol?

the reason Veterans use poppies as their symbol is because when they were fighting the first and Second world war, they were surrounded by fields of poppies (red) so much blood and so much death amids all this beauty, so a man named John Mac Rae ( a Canadian) wrote a beautiful poem called " In Flanders Fields" well worth the read you will probably find the Words in his Bio on google.