The Siege of Groenlo was a siege of Groenlo by Dutch forces under Maurice of Nassau during the Eighty Years' War. It lasted from 11 to 28 September 1597 and ended in the town's capture from its Spanish garrison. After that the troops moved to Bredevoort. It followed an unsuccessful Dutch siege by Maurice in 1595 and formed part of Maurice's successful offensives against the Spanish in 1597. Groenlo was then held by the States until a siege in 1606 by Ambrosio Spinola.