UC-5 had an impressive career, with 29 ships sunk for a total of 36,288 tons on 29 patrols. On August 21, 1915 UC-5 became the first submarine minelayer to penetrate into the English Channel, laying 12 mines off Boulogne, one of which sank the steamship William Dawson the same day. UC-5 went on to lay 6 more mines off Boulogne and Folkestone on 7 September, one of which sank the cable layer Monarch.