The yacht Agawa was built in Leith, Scotland in 1906 by Ramage & Ferguson for William L. Harkness of New York City. Harkness, a well known oil tycoon, leased the ship to the U.S. Navy in 1917 and she was commissioned USS Cythera SP-575 on Oct. 20, 1917. She sailed to Gibraltar and from there escorted convoys through the Mediterranean until returning to the U.S.A. and decommissioning on Mar. 17, 1919.

On Dec. 31, 1941 Mrs. Edith H. Harkness, widow of William, sold the yacht to the U.S. Navy for $1.00 and she commissioned as USS Cythera PY-26 on Mar. 3, 1942. The 212' long yacht was now again a warship. Armed with machine guns and depth charges for anti-submarine patrols. On May 1, 1942 she sailed from Norfolk bound for Pearl Harbor, but she never made it.

Less than 24 hours after leaving port, Cythera was sighted by U-402 about 100 miles off Cape Fear, North Carolina. The boat observed Cythera for two hours before her commander, Kapitänleutnant Siegfried von Forstner, felt that he was in a good position to fire. He sent three torpedoes screaming toward the unsuspecting ship, at least one hit (some sources claim two hits). The explosion broke Cythera in half and she sank rapidly, making things worse for the seventy-one man crew depth charges in the racks went off when they sank to the appropriate depth.

The quick sinking and the explosions of the torpedo and depth charges left only two men alive in the water, Seaman 2nd Class James M. Brown and Pharmacist's Mate First Class Charles M. Carter. The U-boat surfaced and picked the men up making them the first Americans captured by the Germans in the Second World War. They at first thought they were going to be shot in the water, but the German commander was not that kind of man. The two survivors were well treated and mostly allowed to roam around the boat at will. They ate with the crew and found their captors quite polite and civilized seamen.

When they were landed at St. Nazaire and handed over to the Wehrmacht however their treatment was quite different. They were handled roughly and von Forstner apparently made some kind of complaint, which fell on deaf ears. Both men survived the Nazi PoW camps and were liberated in April of 1945. Brown, was in a PoW camp in Bayern (Bavaria) when the U.S. Army rolled up on the camp, according to Brown "At 11 a.m. the Germans turned their guns upside down American GIs came rushing in shooting like cowboys; the swastika was pulled down, the American flag went up. And it seemed to me that out German captors were about as happy as we were that it was over".

Cythera's loss was unknown to the public and indeed to the navy, the first time anyone knew she was missing was when she failed to arrive in the Canal Zone, the navy released the news to the public on June 4, 1942. The families were notified that the men were missing in action for unknown reasons, but weeks later the families of the survivors began to receive letters from the prisoners. It was only then that the fate of Cythera was learned. It was not until early 1943 that the families of the others were told by the navy what had happened to them.

Siegfried von Forstner was later promoted to Korvettenkapitän and awarded the Ritterkreuz having sunk over 63,000 tons of shipping. After receiving the Ritterkreuz only two more ships were lost to his boat, he and U-402 were sunk in October of 1943. Two U.S. Navy ships were named in honor of men on Cythera, USS Rudderow DE-224 and USS Brister DE-327.