The 1345 "Household Ordinance of Edward III" provides a brief summary of the Fleets organized for the Crécy campaign. The South Fleet (which included all English ports south and west of River Thames) consisted of 493 ships with 9,630 mariners. Of these, the "King's Ships" (25 ships with 419 mariners), the ports of Dartmouth (31 ships with 757 mariners), Plymouth (26 ships with 603 mariners), and London (25 ships with 602 mariners) were the largest contingents. The North Fleet (which included all English ports north of River Thames) consisted of 217 ships with 4521 mariners. The port of Yarmouth, with 43 ships with 1095 mariners, was the largest contingent. The definition of a mariner is unclear, as is the difference between a mariner and a sailor. The number of mariners given is about twice that needed to man a ship. Edward's warships carried two crews. The second crew was used for night sailing, for providing a crew for prize ships, and for providing more fighting men.