Key Facts
- Duration
- 19 May – 19 August 1604 (3 months)
- Conflict
- Eighty Years' War and Anglo–Spanish War
- Key territories taken en route
- Cadzand, Aardenburg, IJzendijke
- Spanish relief commander defeated
- Ambrogio Spinola and Luis de Velasco
- Concurrent event
- Fall of Ostend to Spain (1604)
Strategic Narrative Overview
The allied army advanced systematically through the Spanish Netherlands, capturing Cadzand, Aardenburg, and IJzendijke before turning to besiege Sluis, an important Spanish-held inland port. Spain dispatched a relief force under Ambrogio Spinola and Luis de Velasco to break the siege, but Maurice's forces defeated this attempt. Despite tough fighting, the allies maintained the siege. Ostend fell to Spain on 22 September 1604, denying that original relief objective.
01 / The Origins
During the Eighty Years' War, the Spanish besieged the Dutch-allied port of Ostend for three years. To relieve pressure, the States-General and their English allies planned a counter-offensive in the Spanish Netherlands. Prince Maurice of Orange and English commander Horace Vere led a combined army across the Scheldt estuary, aiming to threaten Spanish positions and if possible relieve Ostend while the broader Anglo–Spanish War also raged in the region.
03 / The Outcome
Sluis was captured by the Dutch and English forces by 19 August 1604, compensating for the loss of Ostend to Spain. The seizure of Sluis gave the Dutch Republic a valuable strategic stronghold in the region. The defeat of Spinola's relief force demonstrated Maurice's tactical superiority, and control of Sluis shifted the local balance of power despite the overall continuation of the Eighty Years' War.
Belligerents & Mobilization Analysis
Side A
2 belligerents
Maurice of Orange (Prince Maurice of Nassau), Horace Vere.
Side B
1 belligerent
Ambrogio Spinola, Luis de Velasco.
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.