Queen Elizabeth I’s favourite Henry Jermyn became governor of Jersey in 1644, but the day-to-day running of the island's affairs was conducted by Sir George de Carteret, who succeeded his uncle Sir Philip de Carteret as Bailiff of Jersey in August 1643. Carteret landed on Jersey in November 1643 and drove out the Parliamentarian governor Major Lydcott.
Carteret governed Jersey with great severity, imprisoning Parliamentarian supporters and confiscating their property. Commissioned vice-admiral and knighted in 1645, Carteret conducted a successful privateering operation against English shipping. After the defeat of the King's armies on the mainland, the future Charles II sheltered in Jersey from April to June 1646 upon escaping from Cornwall and the Scilly Isles. When the Prince departed for Paris, his adviser Sir Edward Hyde remained on Jersey for another two years, where he began writing his great history of the civil war.
During the Civil War, the Royalists in Guernsey were blockaded in Castle Cornet while Carteret resumed his privateering activities. Like Sir John Grenville on the Scilly Isles, Carteret continued to raid merchant ships after the declaration of the Commonwealth of England in 1649. Unlike Grenville, however, Carteret did not sanction attacks on Dutch ships.
Charles II arrived in Jersey in September 1649, intending to move from there to lead the Royalists in Ireland. By the end of the year, however, the success of Cromwell's invasion of Ireland had forced Charles to abandon the plan. He returned to France in February 1650.
During the spring of 1651, the Commonwealth government sent an expedition against Sir John Grenville which succeeded in reducing the Scilly Isles by the end of May. This left Carteret's privateers as the last Royalist threat to Commonwealth shipping in the Western Approaches. On 20 September 1651 the Council of State commissioned an expedition against Jersey. Colonel James Heanes was appointed military commander of the invasion.
Expedition sets sail
The Commonwealth expedition sailed from Weymouth in Dorset on 17 October. After being forced back by storms, it finally arrived off St Ouen's Bay in Jersey at noon on 20 October. However, the sea was still too rough for the troops to land. The alarm was quickly raised on the island and Carteret mustered 2,000 militiamen, 300 horse and dragoons, his own company of 130 firelocks and six small field guns, which he deployed on the beach.
The next morning Blake sent a messenger by boat calling on the Royalists to surrender. Fearing that most of his troops had no heart to fight, Carteret ordered his firelocks to open fire on the boat, forcing it to retreat. Blake responded by ordering some of his frigates to sail close inshore and bombard the Royalists. Few casualties were inflicted but the militiamen were terrified and withdrew into the shelter of the sand dunes.
After several hours' bombardment and with no sign of the rough seas abating, Blake sailed south-eastwards around to St Brelade's Bay to see if conditions were more favourable for a landing there. The Royalists followed along the shore. While the rough weather continued, Blake sailed his ships back and forth along the coast to tire and confuse the Royalists, who were forced to march after the ships in case a landing was attempted. Exhausted by marching through wind and rain, and under fire from the Commonwealth fleet, the militia became mutinous and disorganised. Carteret and his officers struggled to keep control at sword point.
Weather and tidal conditions finally allowed the Commonwealth troops to attempt a landing in St Ouen's Bay at 11 pm on 22 October. When de Carteret tried to rally his troops to oppose the landing, he found that two-thirds of his cavalry had deserted and only the St Ouen militia, which was under his direct command, remained in the field. Colonel Edward Bovill led the remaining Royalist cavalry in a charge on the first wave of Commonwealth soldiers while Carteret tried to draw up the wavering militia in support. Bovill's attack drove the landing party back to the water's edge with a number of casualties. The cavalry were about to make a second charge when Bovill was shot and wounded, which threw the Royalists into confusion and gave Colonel Heane time to land more Commonwealth troops. Under sustained fire from Heane's men, the Royalists broke and fled. Carteret escaped to Elizabeth Castle.
Blake secured a safe anchorage for the fleet while Colonel Heane advanced unopposed to St Helier. On 24 October Heane summoned Carteret to surrender but was refused. Elizabeth Castle was regarded as an impregnable stronghold. Situated on a tidal island, it could only be approached across a causeway at low tide. The rocky coastline of the island prevented ships from coming close and the castle was believed to be out of effective artillery range. Leaving a force in St Helier to blockade the castle, Heane marched north to Mont Orgueil, which was held by Sir Philip Carteret, brother of Sir George. On 25 October Heane summoned Mont Orgueil to surrender. Although Sir Philip was defiant, the garrison was reluctant to fight and threatened to mutiny if he refused to negotiate with the besiegers. The terms offered were generous: Sir Philip was allowed to keep his estates in Jersey and the garrison was granted indemnity for any actions carried out during the war. Sixty men who wanted to continue fighting for the Royalists were allowed to join Sir George Carteret in Elizabeth Castle, the rest were given free passage overseas.
During the last week of October 1651, an artillery battery was set up on a low hill outside St Helier and the bombardment of Elizabeth Castle began. However, six demi-cannon, firing 36-pound shot, had little effect on the castle and only succeeded in damaging some outlying earthworks. A further six guns and three mortars were added to the battery in early November. On 9 November, a direct hit by a mortar shell blew up a quantity of ammunition and gunpowder stored in the crypt of a medieval priory that had been incorporated into the castle. The massive explosion killed six men, buried 40 others and destroyed most of the remaining buildings of the priory. Morale in the garrison declined quickly and a number of men deserted, yet Sir George Carteret remained defiant even after Charles II had sent a message giving him permission to surrender. Carteret ordered the evacuation by ship to France of the women in the garrison and hanged a man caught in the act of desertion. By early December, however, provisions were almost exhausted. A blockade by Blake's fleet ensured that there was no possibility of relief.
On 8 December, Carteret finally agreed to open negotiations for surrender. Generous terms were offered, as had become customary with outlying Royalist garrisons. Carteret was allowed to go to France with his money and possessions; his men were also given free passage. The castle was delivered up to the victorious Commonwealth forces at noon on 12 December 1651. With the surrender of Jersey, all Royalist resistance came to end. Blake and Heane's conquest of the Channel Islands was completed when Sir Peter Osborne surrendered Castle Cornet on Guernsey on 17 December under the same terms granted to Carteret.