- Source: 21st Battalion
- Pertempuran Phủ Hoài
- Peperangan gunung
- Terorisme komunis
- Bernard Montgomery
- Insiden Mayaguez
- Sophie, Adipatni Edinburgh
- Korps Ekspedisi Tonkin
- 21st Battalion
- 21st Battalion (Eastern Ontario), CEF
- 21st Battalion (Australia)
- 15th Scottish Reconnaissance Regiment
- Maratha Light Infantry
- Parachute Regiment (India)
- 2/21st Battalion (Australia)
- Manchester Pals
- 1st Surrey Rifles
- Princess of Wales' Own Regiment
21st Battalion may refer to:
21st Battalion (Australia), a World War I ANZAC battalion
2/21st Battalion (Australia), a World War II Australian infantry battalion
21st Battalion (New Zealand), a World War II New Zealand infantry battalion
21st Battalion (Eastern Ontario), CEF, a World War I battalion that formed part of the Canadian Corps
21st Battalion, London Regiment (First Surrey Rifles)
See also
XXI Corps (disambiguation)
21st Division (disambiguation)
21st Brigade (disambiguation)
21st Regiment (disambiguation)
21st Squadron (disambiguation)