Short answers, pulled from the story.
The Siege of Ostend lasted from 1601 to 1604 between Spanish forces and Dutch defenders. It cost a combined total of more than 80,000 dead or wounded, making it the single bloodiest battle of the Eighty Years' War.
Ostend's strategic location on the North Sea coast made it a target for both German and Allied forces. Germany used the harbour to station submarines and naval forces, while the Royal Air Force bombed it repeatedly fearing a German invasion of England. A total of 407 Allied bombs fell on the city.
The Ostend Company was a trading enterprise granted a monopoly over commerce with Africa and the East Indies by Austrian Emperor Charles VI. It was dissolved in 1727 due to diplomatic pressure from the Dutch and British.
The Pact of Ostend was an agreement reached in 1866 at a meeting of exiled Spanish Liberals and Republicans in Ostend. It laid the framework for a major uprising in Spain, which culminated in Spain's Glorious Revolution two years later.
Ostend attracted Belgian kings Leopold I and Leopold II, both of whom spent their holidays in the city during the 19th century. Their patronage led to the construction of the Hippodrome Wellington and the Royal Galleries, and Ostend became known as "the queen of the Belgian sea-side resorts."
Ostend hosted all of the sailing events for the 1920 Summer Olympics, which were held in Antwerp. Only the finals of the 12 foot dinghy took place in Amsterdam. The city also hosted the polo events.