ORDER OF BATTLE // October 13, 1574
Siege of Leiden
Estimated force strength by side, with confidence labels per surviving record.
Forces engaged
2 sides catalogued · combined 26,000 estimated
Dutch rebels
11,000
Medium-confidence figure
Spain
15,000
Medium-confidence figure
Battle context
The Siege of Leiden, conducted by Spanish forces under Francisco de Valdez against the Dutch rebel-held city in South Holland, ended in October 1574 with the city successfully relieved and the Spanish effort defeated. Spain sustained casualties of 2,000 against a force of 15,000, while the Dutch rebels defending Leiden under Pieter Adriaanszoon van der Werff numbered 11,000. The failed siege represented a significant check on Spanish efforts to suppress the Dutch revolt during the Eighty Years' War. Leiden's relief denied Spain control of a strategically positioned city in South Holland and demonstrated that Dutch resistance could withstand sustained Spanish military pressure. Within the broader arc of the conflict — which would continue until 1648 — the outcome reinforced the capacity of the rebellious Dutch provinces to hold key urban centers against the militarily larger Spanish force.
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