on this day, 20 engagements
Battles fought on 21 September
20 engagements in the atlas were fought on 21 September between 1217 and 1944: 18 battles and 2 sieges. Among them: Battle of Karánsebes (1788).
Engagements by date
| Date | Engagement | Place | War |
|---|---|---|---|
| 21 September 1217 | Battle of St. Matthew's Day | Viljandi | Northern Crusades |
| 21 September 1433 | Battle of Hiltersried | Hussite Wars | |
| 21 September 1532 | Siege of Marburg | Maribor | Habsburg–Ottoman wars in Hungary |
| 21 September 1545 | Battle of Fox Bridge | Motoyoshiwara | |
| 21 September 1689 | Battle of Brackett's Wood | North America, Maine | King William's War |
| 21 September 1695 | Battle of Lugos | Lugoj | Great Turkish War |
| 21 September 1745 | Battle of Prestonpans | Edinburgh | Jacobite risings |
| 21 September 1762 | Battle of Brücker Mill | Brücker Mühle | Seven Years' War |
| 21 September 1780 | Battle of Wahab's Plantation | North Carolina | American Revolutionary War |
| 21 September 1788 | Battle of Karánsebes | Caransebeș | Austro-Turkish War of 1788–1791 |
| 21 September 1793 | Battle of Montaigu | Montaigu | War in the Vendée |
| 21 September 1794 | First Battle of Dego | Dego | French Revolutionary Wars |
| 21 September 1795 | Battle of the Diamond | County Armagh | Armagh disturbances |
| 21 September 1848 | Third Siege of Szenttamás | Srbobran | |
| 21 September 1860 | Battle of Palikao | Baliqiao | Second Opium War |
| 21 September 1874 | Battle of Biurrun | Biurrun | Third Carlist War |
| 21 September 1914 | Battle of Ukoko | Cocobeach | World War I |
| 21 September 1918 | Battle of Doss Alto | ||
| 21 September 1939 | Battle of Kamionka Strumiłowa | Kamianka-Buzka | World War II |
| 21 September 1944 | Battle of Porkuni | Porkuni | World War II |
Only engagements recorded to the day are listed. Dates before 1582 are Julian, as recorded.