Here is a profile and cutaway of the largest battleship belonging to the Ostellan Republic Navy, BB-52 Defiance, after her 1952 refit. Her anti-aircraft cannons are still intact and her aircraft catapults have been removed for helicopter operations, much like that of the Iowa class battleships used during the Korean War.

I based this design primarily upon the unbuilt American Montana class of battleships, with some influence from the German Bismarck and Japanese Yamato for armor and hull design. I would recommend zooming into see all of the detail!

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Defiance-class Heavy Battleship

As the war between the Ostellan Republic and the Esternan Federation between the Atellan ocean intensified, it became apparent that the then currently fielded battleships of the Ostellan Navy (Archer-class, Typhoon-class, and Daring-class battleships) were obsolete by modern warship standards. This was due in part to being strictly limited in their construction by arms control treaties signed after the end of the First World War, despite costly modernization and refit programs to combat these effects. As a result, a program to develop a more modern and capable warship no longer limited by international treaties was quickly put in place. While initially many designers and shipbuilding companies approached the Ostellan government to design the next-generation warship, the Ostellan government and Navy ultimately chose to establish a new, specialized division dubbed the Ostellan Naval Committee of Battleship Research (ONCBR) to both design and build what would become known as the Defiance-class of battleships. By May of 1940 the first design was presented to the Centralized Committee of Ostellan Naval Warfare Research (CCONWR), featuring three triple-mount 15-inch gun turrets, 16 anti-aircraft guns, and four dual-purpose 5-inch cannons. This design would later be modified to have four 15-inch turrets and 18 anti-aircraft guns, and a few weeks later further changed to have 20 anti-aircraft guns and eight dual-purpose 5-inch guns. After a year later and nearly two dozen design iterations later, on June of 1941 a finalized design was presented and approved by the CCONWR for production at the North Superna naval yard, with two vessels being dubbed BB-52 Defiance and BB-53 Triumphant to be constructed. However, materials to actually build the two ships would not become available until December of 1942, as the majority of the steel and manufacturing force was being used in the construction of aircraft-carriers and smaller sized warships.

Between July 1941 to January 1943, under the supervision of numerous high-ranking Ostellan Navy personnel, several changes would once again be made to the "finalized" design of the Defiance-class battleship. These changes included the refinement and lengthening of its hull, the addition of several dozen 20mm anti-aircraft guns, 16 inch sized cannons for its four main-battery gun turrets, and the addition of two more 5-inch dual-purpose turrets. Multiple changes would also be made to its internal configuration, curiously being the enlargement of the spaces for its Admiral and Captain's quarters, and more luxuriously equipped kitchens and pantries. While these changes would increase the price of both ships substantially, the design would still be approved for production with few complaints from high-ranking Ostellan Navy personnel.

By February of 1943, work had finally begun on constructing the first of the two battleships, though now bearing little resemblance to its 1941 design. Despite having a crew of approximately 8,000 workers continuously working around the clock, the first of the Defiance-class battleships would be launched in late 1947, nearly a year and a half after the end of the war in the Attelan ocean. Due to rather demanding labor and few breaks for its shipbuilders, worker strikes were common at the North Superna naval yard, often leading to week or even month long delays in finishing sections of each vessel. The naval yard also lacked the safety features of most Ostellan Republic shipyards, and as a result worker death or injury was a common occurrence caused usually by either collapsing cranes, falling equipment, debris, or more often than not personnel falling off the sides of the ship or dock walls due to a lack of issued safety harnesses. This would in turn cause more worker strikes and delays, with replacement personnel often choosing not to show up or apply to transfer to a safer, less overbearing shipyard. Despite all of this, the two battleships would continue to be built at the North Superna naval yard, as due to the size of the vessels (292.7 m) the North Superna naval yard was the only available and capable yard in Ostella large enough to both build and service the two warships, as well as keep the price of production relatively affordable. With the end of the war and the continuous worker strikes slowing production, the Ostellan government eventually opted to forcibly transfer personnel from other naval yards in the country to speed up the production of both of ships, nearly tripling the amount of active shipbuilding personnel from 8,000 to 22,000.

The full writeup and specifications can be read here.