By the middle of 1916 the German Imperial Navy had learned what the British already knew: a moored sea mine is a wonderfully cheap way to kill an expensive ship. UC-45 belonged to the Type UC II class, of which 64 were built, designed almost entirely around the mine-laying mission. Six vertical chutes in the forward hull held three mines each - eighteen in total - that could be released to drop and then float up to their set depth on chains. A trio of forward torpedo tubes and a stern tube added a secondary punch, plus an 88-millimeter deck gun for harassing unarmed merchant ships on the surface. The class was small, slow, and tetchy underwater. The interior was claustrophobic even by U-boat standards, with mines stowed in the same compartment that the crew slept and worked in. Diesel exhaust, battery acid fumes, and the smell of damp metal made every patrol an endurance test.

Ordered on 20 November 1915 and launched on 20 October 1916, UC-45 was commissioned into the Imperial Navy on 18 November 1916 under her serial designation. Her wartime record reads as a list of dates and tonnages, but each entry is a small disaster for somebody. On 19 March 1917 she sank the merchant Pollux of 1,196 gross tons. On 22 March, two in one day - Egenaes and Susanna, both Norwegian. On 23 March she got Blomwaag. April brought Bretagne, Charles Goodanew, and the steamer Louisiana of just over 3,000 tons. May added Saint Hubert and the larger Teie. In June she sank Phemius - 6,699 tons, by far her biggest victim - and the tiny coaster Golden Hope of 67 tons. On 13 July 1917 she sank the 43-ton Afram. Twelve ships, roughly 16,900 tons, all in four months. Most were sunk by mines she had laid days or weeks before; some by gunfire or torpedo on the surface. Behind every entry are sailors who went into a cold North Sea or English Channel.

On 17 September 1917 something went wrong during a routine dive. The exact mechanism is not preserved in the record - a flooded compartment, a stuck vent, an error in the trim tank balance - but the result is. UC-45 went to the bottom of the North Sea and stayed there. Most of her crew were aboard and most did not get out. Submarine accidents in the First World War rarely had survivors; the boats were small, the escape gear primitive, the chances of getting out of a sunken hull a hundred feet down on compressed air essentially nil. UC-45 joined a long list of U-boats lost not to British depth charges or mines but to their own dangerous trade. The Imperial Navy lost more submarines to accidents and mishaps than most peacetime navies have ever owned.

What is unusual about UC-45 is what happened next. A German salvage vessel located the wreck and raised her - no small feat in the North Sea in 1917, with British patrols overhead and weather no friend to lifting operations. The hull was towed home, repaired, refitted, and recommissioned. She re-entered service on 24 October 1918. Two weeks later the war ended. UC-45 had been brought back from the dead to fight a war that no longer existed. Under the terms of the Armistice she was surrendered on 24 November 1918, sailed under British prize crew to England, and broken up at Preston in Lancashire over 1919 and 1920. Her scrap metal went back into British industry. She had killed twelve ships, killed an unknown number of her own crew, been resurrected by salvors who deserved more credit than they ever got, and ended her days dismantled in a yard on the River Ribble.