The Federals out west had both Jefferson brogans as well as contract stuff.MB&S sells a pair that was patterned off a pair that was seen out west.So a either pairs would work.
At the same time,a lot of Federal infantry starting in 1863 started to wear boots.Just before the Atlanta Campaign,Gen. Sherman ordered his infantry to get rid of their boots.Most simply just rolled their trousers down enough so he wouldn't notice.But these are infantrymen,mind you.
South Union Guard
"Always carry a flagon of whiskey in case of snakebite, and furthermore always carry a small snake"~W.C. Fields
"When I drink whiskey, I drink whiskey; and when I drink water, I drink water."~Michaleen Flynn 'The Quiet Man'