since WW2: Annexation of Tibet, Taiwan Strait Crisis, Sino-Indian War, Sino-Vietnamese War.
Also Korean War, 1959 Tibetan Uprising, Nathu La and Cho La clashes, Sino-Soviet Border Conflict, Paracel Islands conflict, Sino-Vietnam border clashes, Johnson South Reef Skirmish, China–India border clashes (Galwan), South China Sea standoffs.
alt Hacker News
Also Korean War, 1959 Tibetan Uprising, Nathu La and Cho La clashes, Sino-Soviet Border Conflict, Paracel Islands conflict, Sino-Vietnam border clashes, Johnson South Reef Skirmish, China–India border clashes (Galwan), South China Sea standoffs.