He commanded U-48 for eight patrols during the early part of the war, sinking 169,709 gross register tons (GRT) of shipping.

He underwent basic military training in the 2nd department of the standing ship division of the Baltic Sea in Stralsund (1 April 1930 – 30 June 1930).

[2] He also served aboard the cruiser Karlsruhe with other future U-boat aces, including Heinrich Lehmann-Willenbrock.

U-2 was assigned to the U-Bootschulflottille (U-boat school flotilla); he spent the next year and a half training with the sub.

On this patrol, which took U-48 to the North Atlantic, southwest of Ireland and to the Rockall Bank before returning to Kiel on 17 September, Leutnant zur See Reinhard Suhren served as 1st watch officer.

[5] Schultze and his crew had already sunk Royal Sceptre on 5 September and Winkleigh three days later for a combined total of 9,908 GRT.

[6] Schultze intercepted the freighter Browning some time later and ordered to pick up survivors from Royal Sceptre.

[7] After returning to base, Schultze gave an interview to William L. Shirer, an American reporter, on 29 September 1939.

[9] Schultze abided by prize law in all but the sinking of Clan Chisholm which sailed in convoy HG 3.

[13] In January 1940 B-Dienst intercepted British naval signals suggesting Ark Royal was a en route through the English Channel.

[18] In a third attack, U-47 commanded by Günther Prien attempted to sink the battleship but failed for the same reason.

[20] On 20 May 1940 Schultze handed command of U-48 over to Hans Rudolf Rösing due to illness stemming from a stomach and kidney disorder.

From October 1940 Schultze became part of the naval staff of the 7th U-boat Flotilla, at St Nazaire, in France.

The presentation was made on 30 June 1941 by Hitler at the Führer Headquarter Wolfsschanze (Wolf's Lair) in Rastenburg (now Kętrzyn in Poland).

[Note 2] On 27 July 1941 Schultze left U-48 to take command of the 3rd U-boat Flotilla operating from La Rochelle, also in France.

In March 1944 he was assigned as commander of Department II, Marineschule Mürwik, where he served to the end of the war.

In August 1945 he was employed by the Allies as commander of the Naval Academy at Mürwik near Flensburg and the Heinz Krey-bearing.

On 2 July 1956, Schultze joined the Bundesmarine of West Germany and served in a string of staff positions.

[28] He then served as Staff Officer Personnel (A1) on the command staff of the naval base, was commander of convoy ships, teaching group leaders at the Naval Academy and head of the volunteer adoption headquarters of the Navy until his retirement on 30 September 1968 with the rank of Kapitän zur See.