Paracel '74 Clash (1974)
The first notable naval battle conducted by China over an island chain in the South China Sea was against the South Vietnamese over the Paracel Islands in 1974. Seizing the opportunity given by the greater Vietnam War, China landed a small force in the contested Paracel islands to test its claim to the islands. When discovered, the South Vietnamese Army and Navy reciprocated leading to a sharp land skirmish and sea battle. Both sides suffered significant casualties but the Chinese prevailed, winning its claim to the islands. This would soon be superseded by South Vietnam losing the greater Vietnam war, however China and Vietnam would find themselves at general war soon after and then skirmishing over the Spratly Island chains in the late 1980s. It would set a precedent of conflict between the two nations, but also the Chinese will to use military force to back historical claims in the region.