After Nobunaga ODA invaded Takashima County in 1572, Nobuzumi ODA governed the county, and the Omizo-jo Castle was built according to the nawabari (castle plan; general term for the layout of a castle and its component structures) developed by Mitsuhide AKECHI in 1579.
元亀3年織田信長が高島郡を進攻すると、天正7年（1579年）織田信澄が高島郡を領し、明智光秀の縄張りで大溝城が築かれた。