TLDR: Battleships were big, armored warships with large guns that dominated naval warfare in the late 19th and early 20th centuries. They were a symbol of naval power and played a major role in diplomacy and military strategy. However, they became less important with the rise of aircraft carriers and other weapons that could easily destroy them. The arms race between countries to build battleships led to major naval battles during World War I, but their significance declined after the war.

Battleships were first called "battleships" in the late 1880s and were initially made of iron. In 1906, the HMS Dreadnought revolutionized battleship design and became the model for future battleships. Battleships were a symbol of national power and were used to intimidate other countries. They played a major role in naval battles during the Russo-Japanese War and World War I.

However, battleships faced challenges from smaller and cheaper weapons like torpedoes, mines, and later, aircraft and guided missiles. The range of naval engagements increased, making battleships more vulnerable. The introduction of aircraft carriers as the leading capital ship during World War II further diminished the importance of battleships.

The Naval Treaties of the 1920s and 1930s limited the number of battleships that could be built. Despite this, both the Allied and Axis powers built battleships during World War II, but they played a less significant role than expected. Battleships were gradually phased out of naval fleets, with the last battleships being used in combat during the Gulf War in 1991. Many World War II-era battleships are now museum ships.

In summary, battleships were once the most powerful and feared warships on the seas. They played a major role in naval warfare and were a symbol of national power. However, advancements in technology and the rise of other weapons made battleships less effective and vulnerable. They were eventually replaced by aircraft carriers as the primary capital ship.