| Conflict: | Siege of Cassel |
| Partof: | the Seven Years' War |
| Date: | March 1761 |
| Place: | Cassel, Hesse-Kassel, Germany |
| Result: | French victory |
| Combatant1: | Hesse-Kassel |
| Commander1: | Duke Ferdinand of Brunswick |
| Commander2: | Duc de Broglie |
The siege of Cassel (March 1761) was a failed attempt by Duke Ferdinand of Brunswick to capture French-held Kassel, the capital of Hesse-Kassel. Brunswick lifted the siege after forces of the Duc de Broglie inflicted heavy casualties on his forces at the Battle of Grünberg, making continuation of the siege untenable.