The ship was named after Matthew Aylmer, commander of HMS Royal Katherine at the Battle of Barfleur in 1692 during the War of the Grand Alliance.

Originally destined for the US Navy as a turbo-electric (TE) type Buckley-class destroyer escort, HMS Aylmer was provisionally given the name USS Harmon (later this name was reassigned to USS Harmon (DE-678), though the delivery was diverted to the Royal Navy before the launch.

On 6 May 1944 the submarine U-765 was sunk in the North Atlantic, at position 52°30′N 28°28′W / 52.500°N 28.467°W / 52.500; -28.467, by depth charges from HMS Aylmer, operating alongside two Swordfish aircraft (Sqdn.

HMS Nabob was able to raise steam and was escorted back (at an average 10 knots (19 km/h)) to Rosyth where she was considered a constructive total loss and used as spare parts.

U-1051 was forced to the surface by the use of depth charges, then a gun battle ensued with U-1051 finally sinking after it had been rammed by HMS Aylmer.

It is entirely clear that the ramming of U-1051 by HMS Aylmer was intentional and that Cdr B.W.Taylor was not removed from command, as has been suggested, shortly after this incident.

A reading of the after-action report makes it clear that the U-1051 was still a belligerent submarine (during the attack by the escorts, U-1051 fired another torpedo at HMS Aylmer).

Borrett, Captain (D) Belfast and attached to the proceedings of HMS Grindall says: It is noted that on surfacing no immediate attempt to evacuate the U-boat was observed.

It is thought quite possible that the U-boat surfaced through faulty trim resulting from confusion in the boat caused by the Hedgehog explosion.

Having regard to these circumstances, it is considered that the decision made by the commanding officer of HMS Aylmer to ram was entirely correct and its execution was faultless.

However, published in The Battle of the Irish Sea, Sir David Gibson has included a picture of HMS Aylmer steaming in to ram the U-boat.