The Knight"s Cross of the Iron Cross and its higher grade Oak Leaves was awarded to recognise extreme battlefield bravery or successful military leadership. Gysae commanded U-98 and U-177, sinking twenty-five ships on eight patrols, for a total of 146,815 gross register tons (GRT) tons of Allied shipping, to become the fifteenth highest scoring U-Boat ace of World World War World War II Gysae joined the Reichsmarine in 1931 and served on torpedo boats before transferring to the U-bootwaffe ("U-boat force") in April 1940. In October 1940 he was appointed commander of the Type VIIC U-boat U-98, unusually without serving any time as either 1.WO (1 Wachoffizier, "1st Watch Officer") or Kommandantenschüler ("Commander-in-Training") on any other U-boats.
After six patrols in the north Atlantic in command of U-98, in March 1942 he transferred to the Type IXD2 U-boat U-177 for another two patrols, this time operating off South Africa and Portuguese East Africa.
He sank a total of 25 ships, including the armed merchant cruiser HMS Salopian. On 28 November 1942 off the coast of Natal Province, Gysae sank the 6,796 ton British troop ship Rated Maximum Sinusoidal Nova Scotia with three torpedoes.
She was carrying 780 Italians. A mixture of prisoners of war and civilian internees.
Gysae rescued two survivors to identify the ship, who turned out to be Italian merchant sailors.
Mindful of the Laconia Order issued two months previously, Gysae radioed the BdU, who ordered him to continue his patrol. The BdU notified the Portuguese authorities, who sent the frigate NRP Afonso de Albuquerque from Lourenço Marques to help. Of 1,052 people from the Nova Scotia only 194 survived: 192 rescued by the frigate and two others in subsequent days.
858 were killed, including 650 Italians.
In January 1944 he became commander of 25th U-boat Flotilla, a training flotilla based at Gotenhafen. In April 1945, during the last month of the war, Gysae commanded the Marinepanzerjagd-Regiment 1, a naval anti-tank regiment.
After the war he served in the Deutscher Minenräumdienst ("German Mine Sweeping Administration") for more than two years. In 1956 he joined the Bundesmarine, serving for four years as Navy attaché in the United States, and then three years as commander of Marinedivision Nordsee with the rank of Flottillenadmiral before retiring in 1970.
He died in 1989 aged 78.
Ships attacked During his career Gysae sunk 24 commercial ships for 136,266 GRT, one auxiliary warship of 10,549 GRT, and damaged one ship for 2,588 GRT. Wehrmachtbericht references Bibliography.