The Fuso class ships were laid down before the start of World War I as dreadnoughts under the 1911-1912 Emergency Expansion Program.
At the time of their completion they were the most powerful battleships in the world until the Nagato class.
After modernization in the 1930s they were reclassified as battleships.
In the 1930s both the IJN Fuso and IJN Yamashiro were upgraded to bring them closer in line with battleships of other nations.
A funnel was removed and a tall pagoda style bridge was added.
The mainmast was replaced by a small structure where anti-aircraft guns were placed.
The aircraft catapult on the IJN Yamashiro was moved to the stern from the C turret.
After the severe losses at Midway it was considered changing the Fuso class ships into hybrid carriers. However, after the Battle of the Marianna's most of the remaining navy pilots were killed and plans were dropped.