At the outbreak of World War II, Brandi continued to serve on minesweeper
M-1 under Bartels.
M-1 transported the
Marinestosstruppkompanie, a reinforced naval infantry platoon, to the battleship prior to the
attack of the Polish base at
Danzig's
Westerplatte in the early morning hours of 1 September 1939. On 1 October 1939, he was promoted to
Oberleutnant zur See (First Lieutenant). Following the
Invasion of Poland,
M-1 undertook various
minefield clearing operations in the
North and Baltic Sea. On 24 February 1940, without prior warning,
M-1 rammed and sank four
Esbjerg based Danish trawlers,
Ejjam (E 92),
Gerlis (E 456),
Mercator (E 348) and
Polaris (E 504) in the vicinity of the
Dogger Bank. Bartels reported to his superiors that no one was rescued due to "military reasons"; 16 fishermen from the then neutral Denmark lost their lives. In April 1940 on
M-1, Brandi participated in
Operation Weserübung, Germany's assault on Denmark and Norway, and was awarded both classes of the
Iron Cross (). On 25 May 1940, Brandi was appointed commander of
M-1. In this command position, Brandi came into contact with the
U-boat arm, providing escort duty to
U-boats leaving and returning to port. He applied for service with U-boat arm but was rejected at first. In April 1941, Brandi applied again, was accepted and started his U-boat training at the Naval Academy Mürwik which he completed on 24 December 1941 at
Neustadt in Holstein. On 25 December 1941, Brandi became a
Kommandantenschüler (Commander-in-training) aboard , which was commanded by
Kapitänleutnant Erich Topp, for one war patrol (25 December 1941 – 27 January 1942). On this patrol before the coast of
Newfoundland,
U-552 sank three ships, the British
Dayrose on 15 January, the US
Frances Salman and the Greek
Maro on 18 January. On 28 January 1942, Brandi was stationed at the
Blohm & Voss shipyard in
Hamburg, for familiarization with , a
Type VIIC U-boat. On 9 April 1942, Brandi commissioned
U-617 in Kiel and completed various trainings with this boat in the
5th U-boat Flotilla.
First patrol, Wolfpack Pfeil For his first patrol (29 August – 7 October 1942), Brandi left Kiel in August 1942, operating in the
Western Approaches before arriving at
St. Nazaire, France in October. There
U-617 was subordinated to the
7th U-boat Flotilla. On this patrol, Brandi claimed four merchant ships sunk. On 7 September, Brandi sank his first ship, the Faroes trawler
Tor II.
U-617 was then part of
Wolfpack Pfeil, which also included , , , , , and , and operated against
Convoy SC 100. On the night 22/23 September, Brandi sank one ship, the tanker
Athelsultan, and on the following day two stragglers for . One of the stragglers sunk by Brandi on 23 September was the formerly Danish steamer
Tennessee. The other straggler, the Belgian steamer
Roumanie, was sunk at 13:58 on 24 September, killing the master, 35 crewmen and 6 gunners; only the chief engineer survived. Brandi rescued the chief engineer in violation of the
Laconia Order issued by
Großadmiral (German Grand Admiral)
Karl Dönitz. On 26 September, Brandi sighted Convoy ON 131, his attack failed due to torpedo malfunctions. On this patrol, Brandi was promoted to
Kapitänleutnant on 1 October 1942. After this patrol, on 8 October 1942, he received the
U-boat War Badge ().
Second patrol, war in the Mediterranean Sea On his second patrol (2–28 November 1942), Brandi was ordered to the
Mediterranean Sea where he was placed under the command of the
29th U-boat Flotilla. His mission in the
Mediterranean theater of operations was to help secure the supply routes for the
Afrikakorps in North Africa. To get to his destination Brandi had to traverse the heavily guarded
Strait of Gibraltar. Brandi made the passage on 8 November 1942 submerged. Nevertheless,
U-617 was discovered by a British
Short Sunderland bomber which dropped two
depth charges, but missed. That day,
British-
American forces invaded
French North Africa in
Operation Torch (8–16 November 1942). At 11:27 on 21 November, Brandi attacked a strong British naval task force, firing a spread of four torpedoes at distance. Following the assault,
U-617 came under attack. Over four hours, 80 depth charges were dropped on
U-617. At 16:00 on 23 November, Brandi unsuccessfully attacked a
cruiser before arriving in
La Spezia on 28 November 1942. Although no ships were actually sunk that day, the
Führer der Unterseeboote Italy (FdU—Leader of U-boat Operations) later credited Brandi with the sinking of one cruiser of French or American origin, and one
destroyer. Additionally the FdU acknowledged that Brandi had torpedoed two freighters, their sinking was assumed. The FdU denied him credit for having severely damaged a battleship.
Third patrol, Knight's Cross On his third patrol (21 December 1942 – 17 January 1943) before the coast of
Cyrenaica, in December 1942, Brandi sank the ocean tug , and two merchant ships,
Annitsa and
Harboe Jensen on 15 January 1943. Following this patrol which ended in
Salamis, the FdU credited Brandi with the destruction of one destroyer, one tug of and one
lighter of unknown tonnage, all three sunk on 28 December 1942. The FdU further acknowledged the sinking of three ships on 30 December of , two ships on 13 January 1943 of , and two more ships on 15 January of . The
Befehlshaber der U-Boote (BdU—U-boats Commander-in-Chief) confirmed this assessment and credited Brandi with the sinking of eight ships totalling and one destroyer. For this achievement, Brandi was awarded the
Knight's Cross of the Iron Cross () on 21 January 1943. The presentation was made by the commanding Admiral
Aegean Sea,
Vizeadmiral (Vice Admiral)
Erich Förste, in La Spezia.
Fourth patrol During his fourth patrol (27 January – 13 February 1943) which started at the
Salamis Naval Base and ended in
Pula, Brandi sank the British
minelayer a few miles from the
Maltese coast on 1 February 1943. Welshman, together with the minelayer and the mine-laying submarine , had been operating against the
Axis supply route between the
Gulf of Tunis and
Sicily. In addition, Brandi also claimed to have sunk four ships from two convoys for a total of . Verifiable were the destruction of the Norwegian freighter
Corona and
Henrik, both sunk on 5 February 1943 from Convoy AW 22.
Fifth patrol, Oak Leaves In April 1943, on his fifth patrol (25 March – 17 April 1943), Brandi claimed the sinking of a
light cruiser, off
Gibraltar. The FdU credited him with the sinking of a , a on 10 April and a troop transport type
Orcades of attacked on 13 April. On this patrol, Brandi was awarded
Knight's Cross of the Iron Cross with Oak Leaves () on 11 April 1943, the 224th officer or soldier of the Wehrmacht so honored. The presentation was made by
Großadmiral Dönitz at the
Wolf's Lair,
Adolf Hitler's headquarters in
Rastenburg.
Sixth patrol In June 1943, on his sixth patrol (31 May – 20 July 1943), a roundtrip from Toulon, with the objective to engage enemy shipping east of Gibraltar before the Algerian coast. On this patrol, the FdU credited Brandi with the unverifiable destruction of an
H-class destroyer.
Seventh patrol, loss of U-617 after British air attack 12 September 1943. In September 1943, in his last patrol in
U-617, Brandi sank , a , off Gibraltar. A few days later, on the night of 10 September, he was attacked near the
Moroccan coast by
Royal Air Force Wellington aircraft from
No. 179 Squadron piloted by
Squadron Leader D. B. Hodgkinson in position damaging
U-617. Three hours later, on 11 September, another No. 179 Squadron aircraft piloted by
Pilot Officer W. H. Brunini dropped more
depth charges. The resultant damage to
U-617 was so severe that Brandi could no longer risk diving. To avoid capture, Brandi decided to sail
U-617 to shallow waters and abandoned ship off
Melilla, Spanish Morocco, in position . After evacuating into rubber boats, the crew managed to reach the shore without loss and were interned by Spanish troops. Brandi was loosely confined in the officers' camp near
Cádiz. With the help of the German
naval attaché in
Madrid, he received a fake passport with the cover name "Albert Bergmann" and from there returned to Germany. The wrecked
U-617, aground offshore, was finally destroyed and sunk by air attack from
Lockheed Hudson bombers from
No. 48 and
No. 233 Squadron and naval gunfire from and .
Patrols on U-380 and U-967, Swords On 19 November 1943, Brandi returned to Toulon and took command of from
Kapitänleutnant Josef Röther.
U-380 was damaged in an aerial attack on 24 November. Three waves of over 100
Boeing B-17 Flying Fortress bombers had targeted the U-boat base at the
military port of Toulon. The
pressure hull was punctured in three places, requiring extended repairs. On 11 December, Brandi began with first test runs before torpedoes and provisions were stored on 18/19 December. Brandi completed one patrol (20 December 1943 – 21 January 1944) with
U-380, it was
U-380 tenth and last patrol before the boat was destroyed on 11 March 1944 in Toulon by a bombing raid of the
United States Army Air Forces (USAAF)
Ninth Air Force. On 24 December, Brandi attacked what he identified as a H-class destroyer. Röll and Besler state that this destroyer may have been the . On his return to Toulon on 21 January, Brandi, due to a navigational error of , ran
U-380 aground. Two
tugboats called in from Toulon had to pull
U-380 free again.
Kapitän zur See (Captain at See)
Werner Hartmann, the new FdU Mediterranean Sea, evaluated Brandi's performance and severely criticized him for his bad performance on this patrol. In particular his report stated that Brandi failed to maintain a proper war diary, which makes it difficult to assess Brandi's decisions. He went on that Brandi's attacks were carried out to passively, avoiding contact with the enemy, apparently diving away too early. Hartmann concluded that
U-380 running aground was caused by "sloppy" navigation. Nevertheless, both the FdU and BdU credited Brandi with torpedoing one destroyer on 23 December and probably having sunk another destroyer on 11 January. On 22 January 1944,
U-380 was taken to the shipyard at Missiessy for a major overhaul of the boat. An attack carried out by the 15th USAAF on 4 February damaged
U-380, extending its planned maintenance time.
U-380 was ready again for sea trials on 8 March. On 11 March, fully equipped and ready again for its next war patrol, it was moored just outside of Missiessy. At 12:00, Toulon came under attack of 120
Consolidated B-24 Liberators of the
47th Bombardment Wing of the Ninth Air Force.
U-380 took a direct hit, killing the
Dieselmaat Jonny Christof and two shipyard employees. In April 1944 Brandi became commander of . During his first and only patrol (11 April – 17 May 1944) with her in May 1944 Brandi, operating against convoy GUS 38, sank the destroyer on the night of 4/5 May 1944 with a
T-5 acoustic torpedo. Two further attacks with acoustic torpedoes on 26 April and 8 May were unsuccessful. Brandi also made a number of claims for sinking ships that cannot be substantiated. Following this he received the
Knight's Cross of the Iron Cross with Oak Leaves and Swords () on 9 May 1944. Brandi was the 66th member of the Wehrmacht and last sailor of the
Kriegsmarine who received this award. The presentation was made by Hitler at the
Berghof in the
Obersalzberg of the
Bavarian Alps near
Berchtesgaden on 20 May 1943.
Ashore Brandi had to surrender command of
U-967 because he had fallen seriously ill with
tonsillitis on his last patrol. On 8 June 1944, he was promoted to
Korvettenkapitän (Corvette Captain), backdated to 9 May 1944. In July 1944, Brandi was then appointed U-
Admiralstabsoffizier (Asto—officer of the admiralty staff) commander of all U-boat operations in the
Gulf of Finland with commanding admiral of the eastern
Baltic Sea in
Helsinki, under the command of Admiral
Theodor Burchardi. Following the loss of the German naval bases in Finland, the German U-boats operated from
Danzig, present-day Gdańsk, and
Gotenhafen, present-day Gdynia. Their primary area of operations was the passage into the Gulf of Finland. In September–October 1944, Brandi had ordered , , , , , , , and into this area of operations. On 21 September and laid a mine barrage before the peninsula
Porkkala which subsequently sank the Finnish cargo ship
Rigel. On 8/9 October,
U-370 sank one
Motor Gun Boat and the Finnish trawler
No. 764,
U-481 sank a Finnish sailboat on 15 October,
U-1165 sank one minesweeper and attacked a submarine convoy,
U-958 sank two Finnish sailboats,
U-1001 torpedoed one trawler on 25 October, and
U-475 sank one patrol boat. In November–December 1944, Brandi dispatched
U-475,
U-958,
U-479,
U-481,
U-679 and
U-1165 into the
Bottenbusen, the northern part of the Gulf of Finland, and to the area between
Hanko and
Rewal.
U-679 sank one escort ship and one mine layer and was sunk by the Soviet anti-submarine vessel
MO-124 on 9 January 1945.
U-481 sank one lighter and probably the on 12 January.
U-637 sank one patrol boat. Brandi was awarded the
Knight's Cross of the Iron Cross with Oak Leaves, Swords and Diamonds () on 24 November 1944 for his leadership of the U-boat fleet. On 18 December 1944, he was promoted to
Fregattenkapitän (Frigate Captain). The presentation was made by Hitler at the
Reich Chancellery in the
Berlin in early January 1945. In the last year of the war, Brandi became chief commander of the
Marinekleinkampfverbände (small naval battle units) in
IJmuiden in the Netherlands. On 6 May 1945, Brandi surrendered to Canadian forces in the Netherlands and was taken
prisoner of war. ==Later life==