The Farside Series by John Dalmas

The Macurdies had been farmers for generations, and Curtis Macurdy would have been content to spend his life with his exoticallybeautiful wife Varia, earning a living by tilling his plot of land in the American Midwest. Varia was from Yuulith, a magical world separated from Earth by only a dimensional barrier that could sometimes be broached.

Curtis Macurdy leads two lives. On earth, he is a farmer; but on the other side of the secret cross-dimensional gate, in the world of Yuulith, he is the invincible mystic warrior, the Lion of Farside. With the war over, Macurdy hopes to return to his life as a farmer. But trouble is growing in Europe as Adolph Hitler rises to power and the Nazis threaten more than the fate of Earth...

Curtis Macurdy passes through a cross-dimensional gate into a land where his peculiarities are honored, not cursed. There he finds old enemies and another war, and discovers that peace carries a steep price. Meanwhile, his old adversary prepares a doomsday weapon.