UC-38 was a Type UC II submarine, a class designed primarily for minelaying rather than torpedo attacks. Ordered on 20 November 1915 and launched on 25 June 1916, she was commissioned into the German Imperial Navy on 26 October 1916. She measured 50.35 metres in length, displaced 427 tonnes on the surface, and carried a crew of twenty-six men. Her equipment included six mine tubes loaded with eighteen UC 200 mines, three torpedo tubes, seven torpedoes, and a deck gun.

The Type UC II was built for stealth and endurance in confined waters, with a dive time of 35 seconds and the capability to operate at a depth of 50 metres. UC-38 operated throughout her career in the Mediterranean theatre, where the supply lines supporting Allied forces in the region made lucrative targets for both mines and torpedoes. Over nine patrols, she was credited with sinking 43 ships. That figure represents a great deal of lost cargo, lost vessels, and lost lives across the Mediterranean.

The Châteaurenault was a protected cruiser built in 1898, repurposed by 1917 to serve as a troopship. On the morning of 14 December she was part of a convoy moving through the Ionian Sea, escorted by Mameluck, Rouen, and Lansquenet. UC-38, under the command of Hans Hermann Wendlandt, intercepted the convoy near Cape Ducato.

The first torpedo hit at 06:47, amidships. The escorts responded: Mameluck and Rouen turned toward the torpedo's origin, and Lansquenet began picking up men thrown into the sea by the explosion. Châteaurenault called her escorts to close in and evacuate personnel; the evacuation was completed by 07:26. UC-38, observing that the cruiser remained afloat, fired a second torpedo at 08:20. The Châteaurenault foundered quickly after the second hit, but the men had been taken off. Approximately 1,162 personnel were rescued by Rouen, Mameluck, Lansquenet, and trawlers that came to the scene. Around ten men from the Châteaurenault are reported to have died.

The depth charges that followed the torpedo attacks breached UC-38's hull badly enough that Wendlandt was forced to surface. Coming up in waters patrolled by the ships he had just attacked, the submarine and her crew faced immediate gunfire. Mameluck and Lansquenet opened fire. Several of UC-38's crew were killed on or near the surfaced submarine as they abandoned ship. The boat went down.

Wendlandt and some of the crew survived and were taken prisoner. The men who died in the sinking of UC-38 that morning — sailors carrying out orders in a war that had already killed millions — were lost in the same stretch of sea where the men of the Châteaurenault had died less than two hours earlier. Both sides suffered losses in the same short action, in the same cold December water.

Both wrecks — Châteaurenault and UC-38 — lie in the Ionian Sea near Cape Ducato. The Châteaurenault wreck has become a dive site, resting in the waters off Lefkada. The UC-38 wreck location is less precisely charted. These were not exceptional events in the context of the Mediterranean U-boat campaign of World War I, which was a sustained, grinding attrition of merchant vessels, troopships, and escort craft. The Mediterranean became one of the most heavily contested submarine battlegrounds of the entire war.

The twenty-six men of UC-38's crew, the ten or so who died aboard Châteaurenault, and the thousands of sailors and soldiers who crossed these waters in 1917 are part of the same catastrophe — a war that consumed Europe and its navies for four years. The action off Cape Ducato lasted a morning. The consequences, for the individuals involved, were permanent.