In an era when siege warfare dominated military campaigns, he and his French counterpart Vauban were the acknowledged experts in designing, taking and defending fortifications.

The family originally came from Kühhornshof [de], near Frankfurt; in 1572, his great-grandfather joined the army of William the Silent, leader of the Dutch Revolt.

[4] Promoted captain in October 1660, Van Coehoorn first saw action in 1665 during the Second Anglo-Dutch War, when he helped repulse an English-funded invasion by the Bishop of Münster.

[5] Van Coehoorn set out his ideas in a public debate over the design of a new fortress at Coevorden with Captain Louis Paen, an officer in the same regiment, who had produced a well-received critique of the Dutch drill manual in 1679.

[1] Few states could afford a large standing army, so permanent fortifications were intended to slow down an opponent, providing time to mobilise reserves.

[7] In 1672, the Dutch were nearly over-run due to the speed with which the French captured fortresses like Nijmegen, and saved only by activating the Hollandic Water Line.

Van Coehoorn accepted the flat terrain of the Netherlands and huge cost of construction meant an effective defence could not rely solely on fortifications.

His recommendation of a defensive barrier in the east, using the IJssel and the Dutch portion of the Lower Rhine, formed the basis of a NATO defence line built in the 1950s, codenamed Plans 'C' for Coehoorn and 'D' for Deventer.

[13] He was present at the capture of Kaiserswerth and Bonn in 1690; his role is unclear but Frederick I offered him a position as Major-General in the Prussian army, which he refused.

Van Coehoorn was put in charge of siege operations and quickly captured the outer City; by mid-August, the Citadel remained largely intact and William was growing impatient.

Nieuwe Vestingbouw was translated into English, French and German among others and reprinted on a regular basis, while his ideas were widely used elsewhere, including Mannheim, Belgrade and Temesvar.

He ...demonstrated one could effectively win a campaign by losing a fortress but exhausting the besieging force...(Boufflers) conducted a classic active defence and contested every advance as best he could.

[17] An often overlooked innovation used by both Vauban and Van Coehoorn was to focus their entire artillery on specific points, rather than the previous practice of targeting multiple areas.

The 1697 Treaty of Ryswick allowed the Dutch to garrison towns in the Spanish Netherlands, including Nieuwpoort, Charleroi, Luxembourg, Mons and Namur.

[22] The armies of the Nine Years War often exceeded 100,000 men, too large for the pre-industrial societies that supported them; Marlborough, Allied commander in the Low Countries, argued one battle was more beneficial than taking 12 fortresses.