Knowing that either of them could die at any moment, they ask Barbossa, as a ship’s captain, to marry them.
The battle at the end of Pirates of the Caribbean: At World’s End is absolutely massive, combining ship-to-ship combat and multiple sword fights going on all at once.
The fight around them is real, but they know they need to do this in case it becomes too late.
The highlight of the entire battle, however, has to be the random wedding that takes place in the middle of it.