The siege of Groenlo was a siege of Groenlo or Grol in 1606 during the Dutch Revolt. It lasted from 3 to 14 August 1606 and ended in the city being captured from the United Provinces by a Spanish Empire force under Ambrosio Spinola. A few months later Prince Maurice attempted to retake the city but failed due to poor planning and an intervention by Spinola. Groenlo would remain in Spanish hands until another siege in 1627.

Siege of Groenlo (1606)
Part of the Dutch Revolt
Groenlo relieved by Spinola, November 1606. Maurice's army (right) sounds the retreat. (In a painting commissioned from Peeter Snayers by Spinola).
Date 3–14 August 1606 (Spinola) 30 October - 9 November 1606 (Maurice) Location Groenlo, Gelderland (present-day the Netherlands) Result 1st Siege: Spanish victory 2nd Siege: Spanish victory
Belligerents
Spain	United Provinces
Commanders and leaders
Ambrosio Spinola	Maurice of Nassau Diederik van Dort
Strength
15,000	1,300-1,400