Sir Samuel Vimes' First of Foot
Any gentleman of the rank of Knight or above may raise a body of armed men in a time of crisis or impending war. In fact, he is obliged to do so by his social standing, and is required to recruit, pay, arm, equip and provision as many men as his purse can stand.
The Patrician reminds Sir Samuel Vimes of this obligation shortly before being obliged to stand down, and allow Ronald Rust to take over the office when war with Klatch loomed over the island of Leshp. After some thought, Sam Vimes raises a rather under-strength Regiment which by happy co-incidence has recruited every member of the Ankh-Morpork City Watch. That is, everyone except Nobby Nobbs, who reasons that if he leaves it till Friday, he'll have been given enough white feathers to stuff a duvet.
As Rust has dissolved the Watch in a time of national emergency, Vimes' raising the Regiment serves two purposes:
i) the Watch carry on being paid, at least at his and Sybil Ramkin's expense, and Vimes can be sure he'll have his full complement of Watchmen to hand when Vetinari returns to office;
ii) Nobody else can sign up or press-gang the Watch to other Regiments led by bloodthirsty maniacs: Vimes reckons they're all safe from this fate once they've signed up in his personal service.