In the grand old days of the British Army, when there were a limited number of "wives" carried on the rations, it was definitely against the King's Regs to marry without permission.

Kipling refers to it in one of his poems about the Boer War:

"There are girls he's married secret, asking no permission to,
"Cause he knew he wouldn't get it if he did."

The quote is from memory, by the way. Please don't start a war if i don't have it exact.