There were quite a few people in Ankh Morpork who wanted the Commander of the City Watch out of the way. He was a nuisance. A variable. These were the type of people who liked to play checkers as if the entire board was red.
But how to get rid of him?
Assassination? No. The Assassins' Guild refused to take any further contracts and hiring anyone from the outside was simply too messy - and besides, the man had proven himself notoriously difficult to kill even with a trained blade pointed in his direction.
Blackmail? Impossible. Sam Vimes was the sort of man to take blackmail and to happily report it to the newspaper that very same evening just to see the look on the other nobles' faces.
Bribery? Laughable. He had a certain way of going absolutely ballistic whenever someone even tried to imply it.
Abduction. It worked. It was simple. It wouldn't be easy, but it would hardly be overly difficult. If there was one thing the commander loved in his life more than his job, it was his family. Even if he wasn't a terribly public man, everyone knew that Sam Vimes wouldn't allow anyone laying a finger on them. He wouldn't dare do anything that would put his son's life in jeopardy, and soon enough they would have even the unbreakable Sir Samuel in the palm of their hands. Moreover, he wouldn't dare kill them, nor would he torture them. Even put under stress, good old Sam Vimes lived and died by the badge. Vimes would simply... fall apart, they were sure, gradually retreat out of the public eye and live the rest of his life a quiet and broken man. No, he wouldn't inflict cruel and unusual punishment on them, not so long as he still had his badge.
But Vetinari would.