My grandfather, who I was led to believe was called Walter Wilson but I have recently found out this his actual name was Walter Dalrymple. He was born in 1892 (give or take a few years) and I was told my aunt of mine, who I have no contact with now, that he changed his name from Dalrymple to Wilson so he could get into the military.

If that's the case, any one want to take a guess as to why he would do that? I'm baffled.