Plan Z

Plan Z was the name given to the planned re-equipment and expansion of the German Navy (Kriegsmarine) ordered by Adolf Hitler on January 27, 1939. The plan called for a Kriegsmarine of by 1945 that was meant to challenge the naval power of the United Kingdom.
 * 1) 10 battleships
 * 2) 4  aircraft carriers
 * 3) 3 battlecruisers
 * 4) 3 old panzerschiffe
 * 5) 12 new panzerschiffe
 * 6) 5  heavy cruisers
 * 7) 36 M-class light cruisers
 * 8) 24 Spähkreuzer-type light cruisers
 * 9) 68 destroyers
 * 10) 90 torpedo boats
 * 11) 249 U-boats

Post-Versailles
Following the end of World War I, the German armed forces became subject to the stipulations of the Treaty of Versailles. For the navy, this meant it was restricted to six pre-dreadnought battleships, six cruisers, 12 destroyers and 12 torpedo boats. The first major ship to be built after the war was the light cruiser GERMAN CRUISER Emden in the early 1920s. This was followed by a further three light cruisers of the : GERMAN CRUISER Königsberg, GERMAN CRUISER Karlsruhe and GERMAN CRUISER Köln, and a further two ships that were modified versions of the Königsberg-class, GERMAN CRUISER Leipzig and GERMAN CRUISER Nürnberg.

Panzerschiff
The Treaty also stipulated that Germany could replace its pre-dreadnought battleships after they reached twenty years of age, but new vessels could displace no more than 10000 LT. In response to these limitations, the Germans attempted to build a powerful heavy cruiser&mdash;classified as a panzerschiff (armored ship)&mdash;that outclassed the new heavy cruisers built by Britain and France. Since the armament British and French designs were bound by the Washington Naval Treaty to a caliber of 8 in, the Germans chose to arm GERMAN CRUISER Deutschland with six 11 in guns. The Germans hoped that by building a ship significantly more powerful than the Allies, they could force the Allies to admit Germany to the Washington treaty system in exchange for cancelling Deutschland, thereby abrogating the naval limitations imposed by Versailles. The French vehemently opposed any concessions to Germany, and therefore, Deutschland and two further units&mdash;GERMAN CRUISER Admiral Scheer and GERMAN CRUISER Admiral Graf Spee&mdash;were built. These were called "pocket battleships" in the outside world.

The panzerschiff concept was by no means new. The same "stronger than faster, faster than stronger" design concept was the basis of the battlecruiser that was widely built prior to World War I. In combat, the battlecruiser was sometimes put into the same lines as battleships, where it could no longer use its superior speed to stay out of trouble. British battlecruisers suffered high losses during the Battle of Jutland and the class as originally conceived was considered obsolete by military planners. Although the British completed HMS Hood (51) already under construction, it was greatly modified and up-armoured. The Washington Naval Treaty classified battlecruisers in the same category of capital ship as fast battleships because that reflected post-World War I naval thinking. However, changes in technology, especially diesel-power plants, re-invigorated the concept, primarily for commerce raiding, allowing the Germans to build ships that evaded the provisions of the Treaty of Versailles on capital ship construction, while being smaller, better armored and still faster than their World War I counterparts. The new designs were widely lauded around the world. In reality they displaced more than 10,000 t. Designed as they were to implement the envisaged likely German war strategy of commerce raiding while avoiding engagements with heavy capital ships, no other major naval power, with differing strategies and needs, copied them. The British with their dependence on seaborne trade did not require commerce raiders. Their needs were for commerce protection, and they built warships suitable for that task. Other major navies did likewise.

Nazi rise to power
In 1933, Adolf Hitler became the Chancellor of Germany. He withdrew from the stipulations of the Treaty of Versailles and began the systematic re-building of the armed forces. The prestige brought by the Panzerschiffe led to two improved vessels, Panzerschiffe D & E to be ordered - these became the GERMAN BATTLESHIP Scharnhorst and GERMAN BATTLESHIP Gneisenau, which were larger than their predecessors, with nine instead of six guns. At the same time, studies were made into the construction of two even larger vessels. These were initially going to be panzerschiffe with 13 in guns, but with the improvements to the French fleet at the time, the new ships were redesigned as full Schlachtschiffe (battleships).

The plan
In 1938 Hitler decided to build a fleet capable of challenging the Royal Navy, in the event of war with Great Britain. He asked the Kriegsmarine to provide plans for such a fleet. Subsequently, it was decided to embark on a large-scale re-building of the German Navy, and the plans X, Y and Z were proposed.

Within the Kriegsmarine, two opposing viewpoints emerged as to the direction of the re-building of the navy:
 * A large battle fleet capable of taking on the most powerful opponents (Britain and France)
 * A large force of U-boats and medium-sized warships such as the panzerschiffe for destruction of the enemy's commercial shipping.

It was pointed out that in order to carry out commerce raiding in the Atlantic Ocean, German ships would have to pass through the North Sea, which was likely to be filled with British battleships. So, the large fleet option was chosen.

Plan Z was a combination of a strong battle fleet capable of challenging the British and a big U-boat fleet for commerce raiding. The plan was initially focused on building large surface ships. If war broke out early in the plan, before the large ships were nearly operational, the large ship building program would be halted. This happened in reality when war started in September 1939. The U-boat production was then given priority and the large ship program was stopped.

In the short time from the introduction of Plan Z on January 27, 1939 up to the beginning of war with the United Kingdom on September 3, 1939 only two of the plan's large ships, H class battleships, were laid down (a third one was only days from receiving its keel). At the time components of the three battlecruisers were in production.

At the beginning of the war the large ships ordered before Plan Z were 1 aircraft carrier, 4 battleships, 3 heavy cruisers and 6 light cruisers which were either ready for action or would be ready in the next months. 1 aircraft carrier, 2 heavy cruisers and 3 light cruisers were in early of stages of construction.

With the outbreak of World War II work on the H-class battleships, the battlecruisers and even on some cruisers and the two aircraft carriers laid down before Plan Z was introduced was halted, because these large and expensive construction projects would require too much of war essential materials and the materials were diverted to the construction of U-boats.