So what is the difference between a Destroyer Escort (DDE) and a Frigate (FRG)? In US Navy terms it is very simple - a Destroyer Escort carries torpedoes a Frigate does not. Turns out that where a ship is built can also have a bearing on this. You can have two ships from the same class that can be either DDE's or FRG's depending on the armament put aboard by the builder. These escort classes came about from the Royal Navy going shopping at BuShips and describing exactly what they wanted. A ship, like the RN River Class, where it would have very good ASW armaments and fair AA armament. The ships needed to be able to cross the Atlantic/Pacific on Convoy duty without refueling. A good chance of meeting a surfaced U-boat required 2-3 guns of a size that could defeat a U-boat. The US built hundreds of these ships in 4-5 different classes. Panagaea put its hand up and said "Could we have some too, please?"
The Commonwealth Navies felt that the main armament of 3x3" with only local control, was too light and would add another gun type to the catalogue of weapons in service. When the ships were received, they would be put through a refit to make them fit for service for Panagaea. The refit would strip out the 3" and replace them with a Hedgehog in A position, a single 4" DP gun in B and X positions. 28mm replaced with 40mm. Twin torpedo launcher replaced with a triple set. A dual purpose gun director for the 4" was placed at the rear of the bridge. The US radar replaced with the better Commonwealth sets available. The US Navy did complain about the length of time it took the Commonwealth Navies to put the Lend Lease ships into service. But words like "cheap' and 'nasty' were bandied about the ships as they had been received.
Panagaea, during 1943-44, received four Cannon class Destroyer Escorts, four Buckley class Destroyer Escorts and 12 Cannon class Frigates.
The twelve Frigates were used on convoy duties between Panagaea and the West Coast of the United States down to Panama and South America. The eight Destroyer Escorts were used to cover the Fleet Replenishment Convoys that kept the Fleet at sea for long periods of time.
