By the spring of 1644, the King held nearly all of the West Country. Plymouth, Poole and Lyme Regis were the only towns of any size still flying Parliament's colours; everywhere else from Bristol to Land's End was Royalist country. Lyme was an unlikely holdout. The town had perhaps three thousand inhabitants, lay in a valley overlooked by hills on three sides, and was built mostly of thatch - exactly the kind of place an army with artillery should have been able to take in days. But Lyme was Puritan to the bone. Charles I's earlier demands for ship money had made enemies of its merchants, and when the war broke out in 1642 two local MPs - Thomas Trenchard and Walter Erle - had claimed the town for Parliament before the King's commanders thought to do anything about it. The mayor, Thomas Ceeley, was made military governor. Then a new arrival took charge of the defences.

Robert Blake had failed to hold Bristol the previous year, but in defeat he had impressed his superiors. Sent to Lyme as a reward, he proved a brilliant engineer. He recognised that the sea-facing fortifications meant nothing if an attacker came from the hills, so he set about building a continuous earthwork around the entire landward side of the town. The Town Line, as it became known, was about a mile long: a deep ditch with a six-foot rampart facing outward, anchored by four blockhouses built of earth and sod, reinforced with timber and stone. The four forts - Newell's, Davie's, Gaitch's and Marshall's - each commanded a sector of the line and were named for their commanders. None of these works survive today; coastal erosion has swallowed at least two of the fort sites whole. But for eight weeks in 1644 they were the only thing standing between Lyme and the King's nephew.

When Prince Maurice's army arrived on 20 April, having burned 144 houses in nearby Beaminster a few days earlier in an accidental fire, Lyme had perhaps five hundred soldiers - half the official garrison. Maurice had at least five times that number. He set up artillery batteries on the west side of town and began bombarding. Ceeley sent out a sortie of 190 men on the fourth day and took a battery. The Royalists rebuilt, fired again, tried three full ground assaults; each was thrown back with significant losses. Throughout the siege, the women of Lyme worked alongside the soldiers. They had dug the earthworks in the months before. Now they reloaded muskets, ran ammunition from blockhouse to blockhouse, tended the wounded, and - in one of the more remarkable details to come down from the sources - put on the coats and hats of dead and wounded men so that, from a distance, the besiegers would believe the garrison larger than it was. The deception worked. Maurice did not press an assault he might have won.

Maurice's fatal weakness was that he could not seal the harbour. Lyme had its back to the English Channel, and Parliament held the Channel. Ships under Captain William Batten brought in powder, food and reinforcements at need - over a hundred men from the Mary Rose and the Ann and Joyce arrived on 29 April alone. By June the prince had been at the wall for nearly two months, his men were sick, his ammunition was thinning, and a relieving Parliamentarian army under the Earl of Essex was marching from the east. Maurice withdrew on 14 June. Parliament voted Lyme a thousand pounds a year in gratitude and unconditional compensation for residents who had lost houses or livelihoods in the siege. Robert Blake went on to become one of the most successful admirals in English history, founder of the tactics that Nelson would later use to such effect. And Lyme Regis quietly returned to the business of fishing and shipbuilding, its mile of earthworks slowly being absorbed back into the fields.