Oddly enough, Bull himself was not particularly militarist. He never saw military service or even owned a handgun. He was said to be generous and thoughtful. He just found something that he really loved doing.
He consulted for everyone, but ran into trouble when he worked for the South Africans. The South Africans were having trouble in Angola at the time (the mid-Seventies). The communist government, aided by Cuban troops and Soviet artillery, was pounding their proxy soldiers to bits. Bull, with the implicit encouragment of the CIA, helped them design a new 155-mm howitzer with 50% more range than anything else at the time. He sold them gun barrels for it and thousands of shells. With the new guns, the South Africans were able to stop the Angolans cold.
Then Carter was elected, and South Africa was no longer in favor. Bull was brought up on charges of illegal arms dealing. On the advice of his lawyer, he pleaded guilty and served six months in prison in 1980.
[link|http://world.std.com/~jlr/doom/bull.htm| Source ]