HMS H4

HMS H4 was a British H-class submarine built by the Canadian Vickers Co., Montreal. She was laid down on 11 January 1915 and was commissioned on 5 June 1915.

After her commissioning, HMS H4 and sister ships HMS H1, HMS H2 and HMS H3 crossed the Atlantic from St. John's, Newfoundland to Gibraltar being escorted by the armed merchant cruiser HMS Calgarian (1913).

H4 sank the U-boat SMU UB-52 in the Adriatic on 23 May 1918.

She was sold on 30 November 1921 in Malta.