Ostend in 1601–1604; La Rochelle in 1627–1628). This resulted in extremely prolonged conflicts. The balance was that, while siege warfare was extremely expensive and very slow, it was very successful—or, at least, more so than encounters in the field. Battles arose through clashes between besiegers and relieving armies, but the principle was a slow, grinding victory by the greater economic power. The relatively rare attempts at forcing pitched battles (Gustavus Adolphus in 1630; the French against the Dutch in 1672 or 1688) were almost always expensive failures. The exception to this rule were the English. During the English Civil War, anything which tended to prolong the struggle, or seemed like want of energy and avoidance of a decision, was bitterly resented by the men of both sides. In France and Germany, the prolongation of a war meant continued employment for the soldiers, but in England, both sides were looking to end the war quickly. Even when in the end the New Model Army—a regular professional army—developed the original decision-compelling spirit permeated the whole organisation, as was seen when pitched against regular professional continental troops the Battle of the Dunes during the Interregnum. Experienced commanders on both sides in the English Civil War recommended the abandonment of garrisoned fortifications for two primary reasons. The first, as for example proposed by the Royalist Sir Richard Willis to King Charles, was that by abandoning the garrisoning of all but the most strategic locations in one's own territory, far more troops would be available for the field armies, and it was the field armies which would decide the conflict. The other argument was that by slighting potential strong points in one's own territory, an enemy expeditionary force, or local enemy rising, would find it more difficult to consolidate territorial gains against an inevitable counterattack. Sir John Meldrum put forward just such an argument to the Parliamentary Committee of Both Kingdoms, to justify his slighting of Gainsborough in Lincolnshire. Sixty years later, during the War of the Spanish Succession, the Duke of Marlborough preferred to engage the enemy in pitched battles, rather than engage in siege warfare, although he was very proficient in both types of warfare. On 15 April 1746, the day before the Battle of Culloden, at Dunrobin Castle, a party of William Sutherland's militia conducted the last siege fought on the mainland of Great Britain against Jacobite members of Clan MacLeod. Strategic