Farnham Castle, near the Surrey town of the same name, was a twelfth-century stronghold that had become the country seat of the Bishop of Winchester, Walter Curle. Most of the surrounding area sympathised with the King. When Charles I raised his royal standard at Nottingham in August 1642 and declared the Earl of Essex - and by extension the whole of Parliament - to be traitors, both sides scrambled to recruit. On 8 September the poet George Wither received a commission as captain of a Surrey cavalry troop. By 14 October, reinforced by what the historian Stephen Manganiello drily calls "weak, poorly-armed squadrons of volunteer horse with but 60 muskets between them," Wither had occupied Farnham Castle for Parliament.

Wither asked repeatedly for more men and more weapons. Neither came. When the Royalist army marched on London in November after the bloodletting at Edgehill, the strategic value of Farnham Castle dropped to zero in the Earl of Essex's calculations, and Wither was ordered to abandon it. On the night of 8 November he evacuated what he could. The next day Royalist forces under Sir John Denham took possession. Denham had been appointed High Sheriff of Surrey by the King earlier that year and issued with a commission of array - a medieval device for raising soldiers that had not been used since 1557. His men proceeded to sack Wither's estate and turn his wife and children out of the house. Wither himself, sent with his troop to Kingston upon Thames, fought at the Battle of Turnham Green on 13 November - the stand-off that turned the King's army back from London.

With the King retreating to Oxford, Essex gave Waller the task of clearing Royalist holdouts from the south-east. Most withdrew. Denham did not. His troops barricaded the castle gate with piles of wood, but the castle itself was not easily defensible, and Denham's men were not soldiers. Waller arrived on 30 November with cavalry and dragoons - no artillery, because he believed he would not need any. He demanded surrender. Denham refused, noting accurately that Waller could not bombard him. Then the assault began, and what should have been a long siege collapsed into three embarrassing hours. The inexperienced garrison would not show themselves on the walls. Without defensive musket fire to keep the attackers back, Waller's men walked up to the gate and attached a petard. Even so, one of his officers, Colonel Anthony Fane, was shot in the cheek - the only Parliamentary casualty of note, who later died of the wound at his home in Kingston. The Royalist courtier Edward Hyde, Earl of Clarendon, wrote afterward that Denham's men "deserved not the name of a garrison."

Denham and his men were marched to London, arriving 3 December. The common soldiers were soon released. Officers were held longer at Lambeth Palace, but Denham was free by March 1643 and joined the King at Oxford. There he learned that Wither - the man whose estate his troops had ransacked - had been captured fighting for Parliament, brought to Oxford, and was now facing execution. Denham petitioned Charles I to spare him. His argument was a joke that became a piece of literary history: "while Wither lives, Denham will not be the worst poet in England." The King relented. Wither was reprieved, and on his release promptly obtained Parliament's permission to seize Denham's estate as compensation for his own ruined property. The two poets had defeated each other off the battlefield as thoroughly as they had each lost theirs.

Waller took £40,000 worth of plunder out of Farnham Castle, along with gunpowder and shoes - the prosaic accumulation of a garrison that had eaten well and fired little. Within the next month he captured Winchester, Arundel, and Chichester, asserting Parliamentary control over Surrey, Sussex, and most of Hampshire. The following spring he was appointed Major-General of the West and sent to claim the south-west for Parliament, though he would soon meet his own setbacks at Cropredy Bridge and elsewhere. Farnham Castle itself became his base of operations. After the war, like so many strongholds Parliament had taken, it was slighted - deliberately damaged so it could never again be defended. Denham retired from soldiering and wrote propaganda for the King. He is best remembered today not for the disgrace of 1642 but for the poem Cooper's Hill, in which the River Thames is famously asked to flow "deep, yet clear, though gentle, yet not dull." A better epitaph, perhaps, than any his military career deserved.