Though trawlers are a class of naval vessel which seldom become conspicuous, owing to so many of them being assigned to unspectacular duties, the Moonstone was decidedly “in the new” in 1940.
An Italian submarine of 800 tons, with a surface speed of 18 knots, the Galileo Galilei (named after the astronomer), was operating in the Red Sea when Italy entered the war. On her first cruise after hostilities begin she was sighted by a British destroyer, which dropped depth charges near her. Slight leakage resulted, but much more serious was the dislocation of the air conditioning plant. So humid did the air become that ultimately the submarine was forced to break surface at frequent intervals. On one of these occasions she was spotted by aircraft, and the Moonstone, an anti-submarine trawler based on Aden, was detailed to deal with her. Depth charges induced the Galilei to break surface, and perceiving the small size and light armament of the trawler, the Italian captain made the decision to fight it out on the surface. Mr. William Moorman, Boatswain, R.N., in command of the Moonstone, opened fire almost simultaneously with the submarine, but with better aim. Her captain killed, the Galilei surrendered, and was brought proudly into Aden with the White Ensign flying over the Italian colours. This was the first enemy submarine captured in the War.
Not only was the submarine a bigger and faster ship, but she mounted two modern 3.9-in. guns against the trawler's single old 4-in. Mr. Moorman was awarded the D.S.C. and ordered to take a course to qualify for commissioned rank. The Moonstone is here seen in the Aden harbour. In May 1941 the Moonstone took part in the operations around Crete.