U-99

The U-99 was a German Type VIIB U-Boat that saw service in the Nazi German Kriegsmarine during World War 2. The boat is known as being one of the most successful U-Boats during the war, attributed with sinking a total of 38 ships for a summary tonnage of more than 244,000 GRT (Gross Registered Tonnage) and also took one ship as a prize and damaging five. The boat was commanded by Otto Kretschmer and was launched on April 12, 1940, and saw eight wartime patrols.

U-99 Characteristics

• Class and type: Type VIIB U-boat
• Displacement: Surfaced 753 Tons / 857 Tons Submerged

• Length: Overall 66.6 meters
• Pressure Hull: 48.8 meters
• Beam: Overall 6.2 meters
• Pressure Hull: 4.7 meters
• Draft:  4.74 meters
• Speed: Surfaced 17.9 knots (33 km/hr), Submerged 8 knots (15 km/h)
• Range: Surfaced: 16,095 km, Submerged: 175 km
• Test depth: 230 m (754 ft).
• Calculated Crush Depth: 250-295 m (820-967 ft)
• Crew:  44 to 48 Officers and Enlisted
• Armament: 5 × 53.3 cm (21 in) torpedo tubes: four bows, one stern
  • 14 × torpedoes or 26 TMA mines
  • 1 × C30 20 mm AA
  • 1 × 8.8 cm (3.5 in) deck gun with 220 rounds

U-99 Initial Training and Combat Patrol

After the U-99 was launched, the crew trained at Kiel and St. Nazaire before departing for her first patrol on June 18^th, 1940. The first patrol would take the boat to the North Sea for operations. During the patrol, the German battleship Scharnhorst’s seaplane attacked the U-99 due to mistaken identity. The U-Boat returned to port on June 25^th, 2012, for repairs in Kiel, Germany.

Second Combat Patrol of the U-99

After two days of repairs in port, the U-99 departed Germany to patrol the west/southwest of Ireland. Two days later, the boat was attacked by German aircraft and had to crash dive, striking the seabed. During the patrol, the boat sank six ships and captured a seventh. On July 8^th, the escorts of Convoy HX 53 dropped 100 depth charges against the U-99, but the boat escaped without significant damage and ended her patrol on July 21^st.

U-99’s Third and Fourth Combat Patrols

The U-99 got underway on July 25^th to patrol the North Atlantic. She is credited with sinking four ships and damaging three. On July 31^st, Convoy OB 191 escorts dropped 20 depth charges on the U-Boat without harming her. The third patrol ended on August 5^th, 1940. The fourth combat patrol for the boat didn’t start for almost a month after the third on September 4th, 1940, for a patrol of the North Atlantic. During this patrol, seven ships were sunk, with the U-Boat returning on September 25^th. Two days later, on September 27^th, the boat suffered minor damage on September 27^th.

World War 2 U-Boat Video

U-99’s Fifth and Sixth Combat Patrols

U-99 turned around for her 5^th combat patrol on October 13^th to patrol the North West Approaches. During the patrol, Convoy SC 7 lost six ships, with another damaged one. The patrol ended on October 22^nd.  A little over a week later, on October 30^th, U-99 returned to the North West Approaches and sank four ships in Convoy HX 83, wrapping up the patrol on November 8th, 1940.

U-99’s 7th Combat Patrol

The next-to-last combat patrol of U-99 occurred between November 27^th and December 12^th. During this underway, the U-Boat patrolled the North Atlantic and sank four ships on convoys HX 90 and OB 252.

The Final Patrol of U-99

The final patrol of U-99 started on February 22^nd, 1941, in the North Atlantic. During the patrol, she sank eight ships in Convoy OB 293 and Convoy HX 112. During the patrol, the U-Boat suffered severe damage. The Captain scuttled the submarine southeast of Iceland to avoid capture by the Allies (of the U-Boat) and lost three sailors on March 17^th, 1941. During the engagement, the boat was attacked by HMS Vanoc and HMS Walker while out of torpedoes. After being driven deep by the attack, Kretschmer had to surface and was rescued along with 40 of his crew to become Allied Prisoners of War.

U-99 War Record

Wolfpack Operations:

During World War 2, German Admiral Karl Dönitz described his strategy of submarine warfare as, Rudeltaktik, which crudely translates to the tactics of a pack of animals. In English, this evolved into the term “Wolfpack.” The usual tactic of the German U-Boats was to patrol separately in pre-designated areas; however, when they thought a convoy was more heavily defended, they would be ordered to assemble in a pack to attack the convoy better if their numbers were sufficient. The U-99 participated in two Wolfpacks during her operational history.

Wolfpack 1: September 20-22, 1940

Wolfpack 2: October 17-19, 1940

War Record

• 35 ships sunk (198,218 (GRT))
• 5 ships damaged
• 1 ship taken as a prize