Ersatz Monarch-class battleship

The Ersatz Monarch-class (Replacement Monarch-class) battleship was a projected new class of four battleships which were to be constructed for the Austro-Hungarian Navy in 1914–1919. Designed to replace the Monarch class of coastal defense ships, each of the battleships were to carry ten 35 cm L/45 guns as their primary armament, a slight improvement over her predecessors, the. The ships were 175.2 m and were designed to displace 24560 t.

The Austro-Hungarian Navy intended to lay down the first vessel in July 1914, but the outbreak of World War I that month caused the Navy to postpone construction until September. Ultimately, none of the vessels were laid down and they were formally cancelled in late 1917. However, four of the 35 cm guns had been built and were transferred to the Austro-Hungarian Army for use on the Italian Front.

History
The Austro-Hungarian Navy ordered the construction of four new battleships to replace the aging in May 1914. As a result, the new class was known by the contract name for the first vessel, Ersatz-Monarch. The ships were to cost 82–83 million kronen each. The class was to be built in two separate shipyards: two battleships were to be built by Stabilimento Tecnico Triestino and two by Ganz & Co – Danubius.

Proposals
The construction of the s had already begun in 1910 when Skodawerke A.G made the first of many attempts to obtain the approval for a new generation of "super" dreadnoughts to replace the aging Monarch-class ships. The original proposal laid forth on 18 April 1911 consisted of 13.5 in 45-caliber guns with three guns in each of the two superimposed turrets.

The Austro-Hungarian Naval Technical Committee later submitted three proposals by Austrian chief naval architect Franz Pitzinger on the general characteristics of the new class in December 1911. The first of the three proposals called for a 22000 LT battleship with 12 in guns. A later proposal had the new class weighing 23000 LT and equipped with 13.6 in guns. The last proposal had the battleship weighing as much as 24100 LT. Despite the first two proposals on the main guns' caliber, the final decision for the caliber was to be a modified and slightly larger version of the original proposal by Skodawerke A.G, with the main turrets to be equipped with 13.78 in to 13.8 in guns. The final design for the main turrets' caliber was influenced by the Imperial German Navy, which had incorporated this caliber on its new s.

By January 1913, the Naval Technical Committee delivered its first official proposal for the new Ersatz Monarch-class battleships. The committee decided to choose the largest of the three initial proposals for the ship's tonnage, with each ship weighing roughly 24,100 tons. The battleships were to be equipped with a total of ten 13.8 in 45-caliber guns, eighteen 5.9 in 50-caliber guns, and twenty-two 3.5 in 45-caliber guns. The main guns were to be between 13.78 in and 13.8 in. It took another year and a half for this final design to be formally approved in July 1914. During this time, a further 12 designs were put forth.

Armament and propulsion
The standard weight for the class was to be 24100 LT per ship. The ships' length would have been 574 ft and the beam 93.5 ft while the draft would have been 51 ft. The four battleships of the Ersatz Monarch-class would have been equipped with four-shaft steam turbines that produced 31000 shp and contained 15 Yarrow water-tube boilers (nine coal-fired and six oil-fired). These engines would have enabled the four battleships to travel at 21 kn. Their total range would have been 5000 nmi while traveling at 10 kn. Each battleship was to be manned by a crew of 1,050 to 1,100 officers and men. According the approved gun designs from January 1913, the members of the Ersatz Monarch-class would have had 10 13.8 in guns, 14 6 in guns, 20 3.5 in guns, two 1.85 in guns and six 21.5 in torpedo tubes.

Armor
The armor plating on the ships would have been 12 in thick around the belt, barbettes, turrets and the conning tower, while the deck would have had 2.85 in thick armor. The underwater defenses of the battleships were a drastic change from previous Austro-Hungarian battleship designs. The new design was similar to recent French and Russian designs. A horizontal armor deck was built into the vessel inwards from the bottom edge of the armor belt, as far as the last vertical bulkheads. The new guns that were approved for the final design were modified to increase the effect of a broadside. However, in order to keep a stable balance between the ships' protection, stability, and firepower, the battleships were to only be equipped with 10 guns. This new layout was unusual, having two turrets with three guns mounted on each of them being superimposed over two twin guns.

Construction and cancellation
With the final design in place, four ships from the class were ordered by the Austro-Hungarian Navy in July 1914. The Austro-Hungarian Navy followed the traditional German custom of not naming the new ships until they were formally launched. As a result, the Navy only referred to them as "replacements" for the old Monarch-class ships, hence the name "Ersatz" (replacement). The four battleships themselves were simply referred to as "Battleships VIII-XI". Because several design sketches that all had slight differences were put forth, the exact final appearance of the ships are not known. However, they all would have been built with raised forecastles in order to give them better seaworthiness than their predecessors of the Tegetthoff class. The battleships would have been equipped with lattice towers that would hold searchlight platforms.

Each battleship would have cost about 83 million kronen. The first battleship would have been laid down in July 1914, but this date was later pushed back to September due to the outbreak of World War I at the end of July. The first battleship, "Battleship VIII," was scheduled to have been completed on 30 June 1917. The second battleship, referred to as "Battleship IX," would have been laid down on 1 January 1915 and launched on 31 December 1917. The third and fourth battleships, "Battleship X" and "Battleship XI," were scheduled to be laid down on 1 June 1916 and completed on 31 May 1919.

The main guns were to be built by Skoda, and while the battleships themselves were never laid down, the guns for one battleship had been ordered prior to the beginning of World War I. These were the only orders that the Austro-Hungarian Navy had placed for any part of the four battleships. It was assumed that following a victorious conclusion to the war in just two months, work on the battleships would resume. As the war continued, four of the main guns that were ordered from the Skoda works were handed over to the Austro-Hungarian Army for use on the Italian front. The rest of the completed main guns were later taken by the French as a war prize following the end of the war. In late 1917, the construction on all four vessels was canceled.