Watcher on the wall
In season 5 of Game of Thrones, Jon Snow “borrowed” a part of the Royal Fleet that belonged to Stannis Baratheon in order to travel to Hardhome. He needed the ships to try and rescue the wildlings trapped there.
But according to the books he didn't need to borrow at all as the Night's Watch already has it's very own fleet of ships. Albeit small, yet useful nonetheless.