Brian Daley’s 1977 The Doomfarers of Coramonde is the first of two books in the Coramonde series.
Springbuck, rightful heir to the throne of Coramonde, is going to have problems taking power. He’s short-sighted and a bit timid, neither of which is a plus in the combat-oriented culture of Coramonde. Also, most everyone at court is conspiring against him, in cahoots with malevolent sorcerer Yardiff Bey.
Providentially, stalwart warrior Duke Hightower appears to save Springbuck! Less providentially, the Duke is almost immediately killed, while Springbuck is temporarily imprisoned.
Meanwhile, in Vietnam, American soldier Gil MacDonald and the crew of the APC Lobo are busy saving the Asian nation from the Communist menace.