. The ship's crew totalled 33 officers and 533 men, exclusive of the air group, in 1939. For self-defence against enemy warships, Hermes had six BL 5.5-inch Mk I guns, three on each side of the ship. All three of her QF Mk V 4-inch anti-aircraft guns were positioned on the flight deck. The ship's waterline belt armour was thick and her flight deck, which was also the ship's strength deck, was thick. Hermes had a metacentric height of and handled well in heavy weather. However, she had quite a large surface area exposed to the wind and required as much as 25 to 30 degrees of weather helm at low speed when the wind was blowing from the side. Service Hermes was laid down by Sir W. G. Armstrong-Whitworth and Company at Walker on the River Tyne on 15 January 1918 as the world's first purpose-designed aircraft carrier, and was launched on 11 September 1919. She was christened by Mrs. A. Cooper, daughter of the First Lord of the Admiralty, Walter Long. The shipyard was scheduled to close at the end of 1919 and the Admiralty ordered the ship towed to Devonport, where she arrived in January 1920 for completion. 1920s Captain Arthur Stopford was appointed as the ship's commanding officer in February 1923 and the ship began her sea trials in August. After fitting-out, Hermes was commissioned on 19 February 1924 and later assigned to the Atlantic Fleet. She conducted flying trials with the Fairey IIID reconnaissance biplanes for the next several months. Hermes participated in the fleet review conducted by King George V on 26 July in Spithead. Afterwards she was refitted until November and then transferred to the Mediterranean Fleet. She arrived at Malta on 22 November and needed some repairs to fix storm damage suffered en route. At this time the ship embarked No. 403 Flight with Fairey Flycatcher fighters and 441 Flight with Fairey IIIDs. Hermes conducted flying exercises with Eagle and the rest of the Mediterranean Fleet in early 1925 before she began a seven-week refit in Malta on 27 March, then sailed for Portsmouth where she arrived on 29 May after her aircraft had flown ashore. Hermes sailed for the China Station on 17 June with 403 and 441 Flights aboard, but made a lengthy pause en route in the Mediterranean during which Captain Stopford was replaced by Captain C. P. Talbot.