Why does the German march song: Im Wald, Im Grünen Walde, share a melody with Glory, Glory Hallelujah?

by Blackadder288
Blackadder288

The Battle Hymn of the Republic, I should have said

Blackadder288

Investigating it a bit; it seems there was an earlier song with the same melody named John Brown's Body? Also, the song heard in Band of Brothers: "gory, gory what a Hell of a way to die."