The three-year Siege of Ostend lasted 1601-1604 and was part of the larger Eighty Years' War (1568-1648) or the Netherlands war of independence from Spain. This untitled bird's-eye view is highly detailed showing troop positions, fortifications and batteries, with several skirmishes in progress. Offshore three large Dutch ships ride at anchor accompanied by numerous smaller sailboats, several sailing up the river to join the battle. This engraving is signed at lower right "G Keller 1604." The history of this conflict is long and complicated, but a worthwhile read here and another article here.
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Condition: B+
Nice impression on sound paper with narrow margins.