[2] During February 1915, she carried out acceptance trials at Kiel,[2] and was attached to the 2d Half-Flotilla in the North Sea in March.

[3] SM U-36's movements and operations were monitored and reported by British Naval Intelligence, better known as "Room 40".

Operating off the north and northwest coast of Scotland, she sank three steamers and almost a dozen smaller vessels.

[2] On the day she was sunk, U-36 intercepted and captured the American windjammer Pass of Balmaha, bearing a cargo of cotton intended for Russia and en route to Kirkwall to be inspected by British authorities.

Pass was refitted as a merchant raider and re-christened Seeadler, commanded by Count Felix von Luckner,[4] soon to become famous for her naval exploits in the Atlantic and Pacific.

U-36 was sunk in the afternoon of 24 July 1915 in combat off the coast of North Rona in the Outer Hebrides with the British Q-ship[2][Note 3] Prince Charles, commanded by Lieutenant Mark Wardlaw, Royal Navy.

The unsuspecting submarine came within about 600 m (660 yd) of the ship when Prince Charles hoisted the British flag of war and commenced firing.

When Luise moved to pick up the survivors floating in the water, Prince Charles fired into her, believing her to be a German resupply vessel.