Great Day In The Morning (1956)

After a card game Southerner Owen Pentecost finds himself the owner of a Denver hotel. Involved with two women, one who came with the hotel, and one newly arrived from the East to open a dress shop, he then has to make even more fundamental choices when, with the start of the Civil War, he becomes one of a small minority in a strongly Unionist town.

IMDb: https://www.imdb.com/title/tt0049278