USS Canopus AS-9 Visiting Brunei

I was leafing through one of my old books and found this first day cover which I bought many years ago. It was a first day cover to commemorate the visit of USS Canopus to Brunei on 30 May 1938. I have no idea what the ship is or what it was doing here in Brunei but I checked up on USS Canopus and found this from US Navy's website about the ship:

USS Canopus (AS-9), 1922-1942. Originally USS Santa Leonora (ID # 4352-A), 1919-1919, and S.S. Santa Leonora (American Passenger Liner, 1919)

Santa Leonora, a 5102 gross ton passenger liner built at Camden, New Jersey, for W.R. Grace & Company, was taken over by the Navy upon completion in July 1919 and placed in commission at that time as USS Santa Leonora (ID # 4352-A). She was briefly employed as a trans-Atlantic troop transport before being decommissioned and transferred to the U.S. Army in September 1919.
The ship was reacquired by the Navy in November 1921 and, following conversion to a 5975 ton (displacement) submarine tender, commissioned as USS Canopus (AS-9) in January 1922. Following several months service with the Atlantic Fleet, she steamed to the Panama Canal Zone and subsequently to the West Coast. In mid-1923 Canopus went to Pearl Harbor, Hawaii, and in the Fall of 1924 accompanied Submarine Division 17 to the Far East. During the next seventeen years, the tender supported the peacetime operations of Asiatic Fleet submarines in the Philippines, Chinese waters, and elsewhere in the western Pacific region.

When Japanese attacks opened the Pacific War in December 1941, Canopus was in Manila Bay. Though hit by enemy aerial bombs in late December and early January, she worked tirelessly to support the hard-pressed U.S. and Philippine defenders of the Bataan peninsula. Many members of her crew, part of an impromptu naval infantry battalion, directly battled Japanese army forces, while her boats were armed and armored to serve as inshore gunboats. On 9 April 1942, when the fall of Bataan made her further use impossible, USS Canopus steamed out into deep water and was scuttled. Many of her men were evacuated to Corregidor, where they continued to fight until that fortress surrendered on 6 May 1942.

 Credit: Department of the Navy