Plan Z was the re-equipment and expansion of theKriegsmarine (German navy) ordered byAdolf Hitler in early 1939. The fleet was meant to challenge the naval power of theUnited Kingdom, and was to be completed by 1948. Development of the plan began in 1938, but it reflected the evolution of the strategic thinking of theOberkommando der Marine (Naval High Command) over the two decades followingWorld War I. The plan called for a fleet centered on tenbattleships and fouraircraft carriers which were intended to battle theRoyal Navy. This force would be supplemented with numerous long-rangecruisers that would attack British shipping. A relatively small force ofU-boats was also stipulated.
WhenWorld War II broke out in September 1939, almost no work had been done on the new ships ordered under Plan Z. The need to shift manufacturing capacity to more pressing requirements forced theKriegsmarine to abandon the construction program, and only a handful of major ships—all of which had been ordered before Plan Z—were completed during the war. Nevertheless, the plan still had a significant effect on the course of World War II, in that only a few dozen U-boats had been completed by the outbreak of war. AdmiralKarl Dönitz's U-boat fleet did not reach the 300 U-boats he deemed necessary to win a commerce war against Britain until 1943, by which time his forces had beendecisively defeated.
Following the end ofWorld War I, the German armed forces became subject to the restrictions of theTreaty of Versailles. For the newReichsmarine, this meant it was limited to sixpre-dreadnought battleships, six oldlight cruisers, 12destroyers and 12torpedo boats. A further two pre-dreadnoughts, two cruisers, and four destroyers and torpedo boats apiece could be kept in reserve.[1] The first major ship to be built after the war was the light cruiserEmden in the early 1920s. This was followed by a further three light cruisers of theKönigsberg class:Königsberg,Karlsruhe andKöln, and a further two ships that were modified versions of theKönigsberg class,Leipzig andNürnberg.[2] At the same time, the Germans created adummy corporation,NV Ingenieurskantoor voor Scheepsbouw (IvS), in the Netherlands to secretly continue development of submarines.[3] This was in violation of Article 191 of the Treaty of Versailles, which prohibited Germany from possessing or building submarines for any purpose.[4] IvS built several submarines for foreign navies, including the TurkishGür, which was the basis for theType I U-boat, and the FinnishVesikko, which was the prototype for theType II U-boat.[5]
The Treaty also stipulated that Germany could replace its pre-dreadnought battleships after they reached twenty years of age, but new vessels coulddisplace no more than 10,000long tons (10,160 t).[6] In response to these limitations, the Germans attempted to build a powerful heavy cruiser—classified as apanzerschiff (armored ship)—that outclassed the new heavy cruisers built by Britain and France. While British and Frenchheavy cruiser designs were bound by theWashington Naval Treaty (and subsequentLondon Naval Treaty) to a caliber of 20.3 cm (8 in) on a displacement of 10,000 tons, the Germans chose to armDeutschland with six 28 cm (11 in) guns. The Germans hoped that by building a ship significantly more powerful than the Allies had, they could force the Allies to admit Germany to the Washington treaty system in exchange for cancellingDeutschland, thereby abrogating the naval limitations imposed by Versailles. The French vehemently opposed any concessions to Germany, and therefore,Deutschland and two further units—Admiral Scheer andAdmiral Graf Spee—were built.[7]
In 1932, theReichsmarine secured the passage of theSchiffbauersatzplan ("Replacement ship construction program") through theReichstag. The program called for two separate production phases, the first from 1930 to 1936, and the second from 1936 to 1943. The latter phase was secretly intended to break the Versailles restrictions.[8] The following year,Adolf Hitler became theChancellor of Germany. He unilaterally withdrew from the restrictions of the Treaty of Versailles and began the systematic re-building of the armed forces. The prestige brought by thePanzerschiffe led to two improved vessels, theD class, to be ordered. These ships were cancelled and reordered as the battleshipsScharnhorst andGneisenau,[9] which were 32,000-long-ton (32,510 t) ships armed with nine 28 cm guns and much greater armor protection than their predecessors.[10] In 1935, Hitler signed theAnglo-German Naval Agreement, which permitted Germany to build up to 35 percent of the strength of theRoyal Navy in all warship categories.[11] The initial designs for two follow-on ships—theBismarck class—initially called for a displacement of 35,000 long tons (36,000 t) with 13 in (330 mm) guns, but to counter the two new, FrenchRichelieu-class battleships, the new ships were significantly enlarged, to a displacement of over 41,000 long tons (42,000 t) and 15 in (380 mm) guns.[12]
The postwar German navy was conflicted over what direction future construction should take. In September 1920,Konteradmiral (Rear Admiral)William Michaelis issued a memorandum laying out the goals of the newReichsmarine; these goals emphasizedcoastal defense rather than significant expansion. The German Army viewedPoland as the primary future enemy, and the Navy assumed that in a conflict with Poland, France would support Poland. Thus, theFrench Navy would be the most likely opponent for theReichsmarine; Britain was expected to remain neutral in such a conflict. The construction of warships through the mid-1930s was primarily directed against the perceived French threat.[13] Any hypothetical U-boats would generally support the main fleet rather than embark on a commerce-raiding campaign, and any raiding would be done strictly according tocruiser rules.[14] This view remained the established orthodoxy until the mid-1930s, when then-Kapitän zur See (Captain at Sea)Karl Dönitz came to command theU-boat arm.[15] Dönitz advocated a return tounrestricted submarine warfare and the adoption ofwolfpack tactics to overwhelm convoy defenses.[16]
In the 1920s, the question arose over what to do with the cruisers that would presumably be abroad on training cruises when a war would break out. The high command decided that they should operate as independent commerce raiders. WhenVizeadmiral (Vice Admiral)Erich Raeder became the head of theReichsmarine in 1928, he fully endorsed the concept of long-range surface raiders. This was in large part due to his service in World War I as the chief of staff toVizeadmiralFranz von Hipper, where he saw the fleet rendered impotent by the crushing British naval superiority.[8] By the late 1930s, Hitler's aggressive foreign policy made conflict with Britain increasingly likely, particularly after theMunich crisis of September 1938. The path toward a major fleet expansion was paved shortly thereafter, on 14 October, whenGeneralfeldmarschall (Field Marshal)Hermann Göring announced a colossal armament program to dramatically increase the size and power of the German armed forces. The plan was to be completed by 1942, by which time Hitler planned to go to war against the Anglo-French alliance.[17] He nevertheless assured Raeder that war would not come until 1948.[11]
Hitler ordered that completion ofBismarck andTirpitz be expedited, along with six newH-class battleships yet to be laid down. These eight battleships would form the core of a new battle fleet capable of engaging the British Royal Navy.[11] Raeder meanwhile believed that Britain could be more easily defeated through the surface raider strategy he favored. The initial version of his plan was based on the assumption that the fleet should be centered onpanzerschiffe, long-range cruisers, and U-boats to attack British commerce.[11] These forces would tie down British naval power and allow a smaller number of battleships to operate in the North Sea. This first draft was called Plan X; a pared-down revision was renamed Plan Y, but Hitler rejected Raeder's proposed construction plan. This led to Plan Z, which featured the more balanced fleet centered on the battleships Hitler sought,[18][11] which he approved on 27 January 1939. In addition to the six new battleships Hitler demanded, the plan called for eight newpanzerschiffe of theDeutschland type and 249 U-boats, with construction spread over the following nine years. By 1948, the German fleet was to include a total of 797 ships; the cost of the program amounted to 33 billionreichsmarks spent over the span of nine years.[17] Further revisions to the numbers of cruisers and other craft were approved on 1 March. Raeder nevertheless retained his operation philosophy of using the battleships and aircraft carriers in task forces to support thepanzerschiffe and light cruisers attacking British merchant traffic, rather than directly attacking the Royal Navy in apitched battle.[11]
The plan, approved by Hitler on 27 January 1939,[19] called for a surface fleet composed of the following vessels, which included all new ships built in the 1920s and 1930s:[11]
| Type | Projected | Completed |
|---|---|---|
| Battleships | 10 | 4 |
| Battlecruisers | 3 | 0 |
| Aircraft carriers | 4 | 0 |
| Panzerschiffe | 15 | 3 |
| Heavy cruisers | 5 | 3 |
| Light cruisers | 13 | 6 |
| Scout cruisers | 22 | 0 |
| Destroyers | 68 | 30 |
| Torpedo boats | 90 | 36 |
| Total | 230 | 82 |
These figures included the fourScharnhorst- andBismarck-class battleships already built or building, the threeDeutschland-classpanzerschiffe and the six light cruisers already in service.[11] To complete the core of the Plan Z fleet, six H-class battleships, threeO-class battlecruisers, twelveP-classpanzerschiffe, and twoGraf Zeppelin-class aircraft carriers with two more of a new design, were to be built.[20][21] The five ships of theAdmiral Hipper class fulfilled the mandate for heavy cruisers, while theM class of light cruisers would fulfill the requirement for light cruisers.[22] TheSpähkreuzer 1938 design would form the basis for the fleet scouts ordered in the program.[23] The plan also called for extensive upgrades to Germany's naval infrastructure to accommodate the new fleet; largerdry docks were to be built atWilhelmshaven andHamburg, and much of the island ofRügen was to be removed to provide a large harbor in the Baltic. Plan Z was given the highest priority of all industrial projects.[24] On 27 July 1939, Raeder revised the plan to cancel all twelve of the P-classpanzerschiffe.[21]
In the short time from the introduction of Plan Z to the beginning of war with the United Kingdom on 3 September only two of the plan's large ships, a pair of H class battleships, werelaid down; material for the other four ships had started to be assembled in preparation to begin construction but no work had been done.[25] At the time components of the three battlecruisers were in production, but their keels had not yet been laid down.[26] Two of the M-class cruisers had been laid down, but they were also cancelled in late September.[27] Work onGraf Zeppelin was cancelled definitively in 1943 when Hitler finally abandoned the surface fleet after theBattle of the Barents Sea debacle.[28]
Since the plan was cancelled less than a year after it was approved, the positive effects on German naval construction were minimal. All of the ships authorized by the plan were cancelled after the outbreak of war, with only a few major surface vessels that predated the plan completed during the conflict. These includedBismarck andTirpitz, along with the heavy cruisersBlücher andPrinz Eugen. Without the six H-class battleships or the four aircraft carriers, theKriegsmarine was once again unable to meet the Royal Navy on equal terms.[29]
Most of the heavy ships of theKriegsmarine were used as commerce raiders in the early years of the war. Two of thepanzerschiffe,Deutschland andGraf Spee, were already at sea at the outbreak of war; the former found little success and the latter was ultimately trapped and forced to scuttle after theBattle of the River Plate in December 1939.[30][31] From October 1940 to March 1941,Admiral Scheer went on her own raiding operation and captured or sank seventeen ships, which made her the most successful of the Germancapital ship surface raiders in the entire war.[32][33][34]Scharnhorst andGneisenau conductedOperation Berlin, a major sortie into the Atlantic in early 1941.[35]Bismarck andPrinz Eugen went on the last Atlantic raiding mission,Operation Rheinübung, in May 1941.Bismarck sank the British battlecruiserHMS Hood but washerself sunk three days later.[36][37] The loss ofBismarck led Hitler to prohibit further sorties into the Atlantic; the remaining capital ships were concentrated in Norway for use as afleet in being and to threaten convoys to theSoviet Union on theMurmansk Run.[11]
Despite the fact that Plan Z produced no new warships in time for World War II, the plan represented the strategic thinking of theOberkommando der Marine (OKM—"Naval High Command") at the time. Most significantly, the OKM favored surface combatants over the U-boats Dönitz needed for hissubmarine campaign in the North Atlantic, which left him with only a handful of submarines at the start of war.[18] The twoScharnhorst-class battleships cost close to 150 millionreichsmarks apiece, and the twoBismarck-class ships cost nearly 250 millionreichsmarks each;[38] for this amount of money, the Germans could have built more than a hundred additionalType VII U-boats.[39] The shift to the submarine war was not definitively made until 1943, by which time the campaign had already been lost.[40][41]
The feasibility of the plan had never been considered by Raeder andKriegsmarine planners; construction of the ships themselves was not a concern, assuming sufficient time had been available. But securing thefuel oil necessary to operate the fleet likely was an insurmountable problem. Fuel consumption would have more than quadrupled between 1936 and the completion of the program in 1948, from 1.4 million tons to approximately 6 million tons. And the navy would have to construct some 9.6 million tons worth of storage facilities for enough fuel reserves to allow for just a year of wartime operations; longer conflicts would of course necessitate an even larger stockpile. Compared to the combined fuel requirements of theKriegsmarine,Heer (Army),Luftwaffe (Air Force), and the civilian economy, the projected domestic production by 1948 of less than 2 million tons of oil and 1.34 million tons ofdiesel fuel is absurdly low.[42]