Karl Dönitz[?] (pronounced ['dø?n?ts]) (September 16, 1891 – December 24, 1980) was a naval leader in Germany during World War II. Despite never joining the Nazi Party, Dönitz attained the high rank of Grand Admiral (Großadmiral) and served as Commander in Chief of Submarines (Befehlshaber der Unterseeboote or B. d. U.), and later Commander in Chief of the German War Navy (Oberbefehlshaber der Kriegsmarine). Under his command, the U-boat fleet fought the famous Battle of the Atlantic. He also served as President of Germany for twenty days following Adolf Hitler's suicide. Controversially, he was charged and convicted of war crimes and served a sentence of ten years for his part in the unrestricted submarine warfare conducted by Germany in the North Atlantic.

Early life and career
Dönitz was born in Grünau near Berlin to Emil Dönitz and Anna Beyer (d. March 6, 1895). His father was an engineer. Karl had an older brother named Friedrich Dönitz. In 1910, Dönitz enlisted in the German Imperial Navy (Kaiserliche Marine), becoming a sea-cadet (Seekadett) on April 4. On April 15, 1911, he became a midshipman (Fähnrich zur See), the rank given to those who had served for one year as officer's apprentice.
Karl Dönitz as an Oberleutnant aboard U-39 in World War IOn September 27, 1913, Dönitz was commissioned as an ensign (Leutnant zur See). When World War I began, he served on the light cruiser SMS Breslau in the Mediterranean Sea. In August 1914, Breslau began operating out of Constantinople (Istanbul) (part of the Ottoman Empire), engaging Russian forces in the Black Sea. On March 22, 1916, Dönitz was promoted to second lieutenant (Oberleutnant zur See); in October of that year he was transferred to the small submarine UC 68.
On 4 October 1918, Dönitz was captured by the British; he remained a prisoner of war in a British prison camp until his release in July 1919, and returned to Germany in 1920. While back in Germany, Dönitz continued his naval career, and became a first lieutenant (Kapitänleutnant) on January 10, 1921. He commanded torpedo boats by 1928, becoming a lieutenant commander (Korvettenkapitän) on November 1 of that year.
On 1 September 1933, Dönitz became a full commander (Fregattenkapitän), and in 1934 was put in command of the cruiser Emden, the ship on which cadets and midshipmen took a year-long world cruise in preparation for a future officer's commission. The ship returned to Germany at Wilhelmshaven in July 1935, and on 1 September Dönitz was promoted to captain (Kapitän zur See). Dönitz was placed in command of the 1st U-boat flotilla, Wediggen, which comprised three U-boats: U 7, U 8, and U 9.

Before World War II
Prior to the war, Dönitz had pressed for the conversion of the German fleet to one that would be made up almost entirely of U-boats. He advocated a strategy of attack only against merchant shipping, targets that were relatively safe to attack. He pointed out that destroying Britain's fleet of oil tankers would starve the Royal Navy of supplies needed to run their ships, which would be just as effective as sinking them. He claimed that with a fleet of 300 of the newer Type VII U-boats, Germany would knock Britain out of the war. In order to deal with the ever-present escort ships, he proposed grouping several subs together into a "wolf pack," overwhelming the defence.
At the time many felt that such talk marked a weakling, and this was true of Dönitz's commander, Grand Admiral Erich Raeder. The two constantly fought for funding priorities within the Navy, while at the same time fighting with Hitler's friends such as Hermann Göring in the Luftwaffe, who received much attention. Raeder had a somewhat confusing attitude; notably he apparently did not believe the German fleet of capital ships was of much use, commenting at one time that all they could hope to do was to die valiantly. Dönitz had no such fatalism.

Role in World War II
When the war started in 1939, Dönitz had recently been appointed commodore (Kommodore) on January 28 and commander of submarines. The German Navy was unprepared for war, having anticipated the war to begin in 1942, as decided in previous war plans. At the time, Dönitz's U-boat force included only 50 boats, many of them short-range. He made do with what he had, while being harassed by Raeder and Hitler calling on him to dedicate boats to military actions operating against the British fleet directly. These operations were generally unsuccessful, while the other boats continued to do well against Dönitz's primary targets of merchant shipping.
On September 1, 1939, Dönitz became a Rear Admiral (Konteradmiral); on September 1 the following year, he was made a Vice Admiral (Vizeadmiral).
By 1941 the delivery of new Type VII U-boats had improved to the point where operations were having a real effect on the British wartime economy. Although production of merchant ships shot up in response, improved torpedoes, better boats, and much better operational planning led to increasing numbers of "kills." On December 11, following the attack on Pearl Harbor, the United States (on whom Hitler had declared war) joined the war. Dönitz immediately planned for Operation Drumbeat against the eastern coast shipping, which was carried out the next month with dramatic results.
On at least two occasions, Allied success against U-boat operations led Dönitz to investigate possible reasons. Among those considered were espionage and Allied interception and decoding of German Navy communications (the Naval version of Enigma, etc.). Both investigations into communications security came to the conclusion that espionage was more likely, if Allied success had not been accidental. Nevertheless, Dönitz ordered his U-boat fleet to use an improved version of the Enigma machine (intended to be even more secure) — the M4 — for communications within the Fleet, on February 1, 1942. The Navy was the only branch to use the improved version; the rest of the German military continued to use their then current versions of Enigma. The new network was termed Triton (Shark to the Allies). For a time, this change in encryption between submarines caused considerable difficulty for Allied codebreakers; it took ten months before Shark traffic could again be read (see also Ultra and Cryptanalysis of the Enigma).
By the end of 1942, the production of Type VII boats had increased to the point where Dönitz was finally able to conduct mass attacks by packs of submarines, which became known as "Rudel" ("pack"). Allied shipping losses shot up tremendously, and there was serious concern for a while about the state of British fuel supplies. In 1943, Dönitz replaced Erich Raeder as the Commander in Chief of the German War Navy (Oberbefehlshaber der Kriegsmarine).
During 1943, the war in the Atlantic turned against the Germans, but Dönitz continued to push for more U-boat construction and technological development. At the end of the war the Nazi submarine fleet was by far the most advanced in the world, and late war examples such as the Type XXI U-boat served as models for Soviet and American construction after the war.
In a way, Dönitz helped bring about the loss of his U-boats. He was a very involved man, often contacting U-Boats up to seventy times a day with questions such as their position, fuel supply, etc. Eventually, the Allies were able to develop technology which allowed them to use triangulation to lock on to an U-Boat while using its radio, forcing them to submerge and then depth charge them.
Both of Dönitz's sons died during World War II. His younger son, Peter, was a watch officer on U-954 and was killed on May 19, 1943, when his boat was sunk in the North Atlantic with the loss of its entire crew. After this loss, Peter's older brother, Klaus, was allowed to leave combat duty and began studying to be a naval doctor. Dönitz lost Klaus almost a year after Peter died, on May 13, 1944. Klaus convinced his friends to let him go on the fast torpedo attack boat S 141 for a raid on the Selsey off the coast of England on his 24th birthday. The boat was destroyed and Klaus died, even though six others were rescued.

Hitler's Successor
In his last testament, Adolf Hitler surprisingly designated Dönitz as his successor as Head of State (Staatsoberhaupt), a choice that shows how distrustful Hitler had become of Hermann Göring and Heinrich Himmler in the final days of the war in Europe. Significantly, Dönitz was not to become Führer, but rather President (Reichspräsident), a post Hitler had abolished years prior. Propaganda Minister Joseph Goebbels was to become Head of Government and Chancellor of Germany (Reichskanzler). Hitler committed suicide on April 30, 1945 and Goebbels followed suit a day later.
Dönitz became the sole representative of the crumbling Reich. The rapidly advancing Allied forces limited his government's jurisdiction to an area around Flensburg near the Danish border, where Dönitz's headquarters were located, along with Mürwik. Accordingly his administration was referred to as the Flensburg government. On May 7, 1945 he authorized the Chief-of-Staff of the German Armed Forces, Colonel-General Alfred Jodl, to sign the unconditional surrender documents for all German forces to the Allies. The surrender documents included the phrase "All forces under German control to cease active operations at 2301 hours Central European Time on 8 May 1945." The next day, shortly before midnight, Jodl repeated the signing in Berlin at Zhukov's headquarters and at the time specified the end of World War II in Europe occurred.
Dönitz appointed Ludwig von Krosigk as Chancellor (Reichskanzler) and they attempted to form a government. During his brief period in office Dönitz devoted most of his efforts to ensuring the loyalty of the German armed forces and trying to ensure German troops would surrender to the British or Americans and not the Soviets, fearing vengeful Soviet reprisals. However his government was not recognized by the Allies and was dissolved when its members were captured and arrested by British forces on May 23, 1945, at Flensburg.