After the death of Oliver Cromwell and the short, unhappy rule of his son, King Charles II assumed the English throne in 1660. The restoration of the monarchy to the house of Stuart after the English Civil War brought a Catholic back to the throne of the predominantly Protestant nation. Although his reign was relatively uneventful, the accession of his son, Charles, duke of York, to the throne as James II in 1685 was a cause of some disquiet. James was intensely Catholic and began a campaign to increase the authority of the Church throughout the nation. When James fathered a son in 1688, the prospect of a continued Catholic dynasty was more than many Protestants could face. Parliament invited King William of Orange in the Netherlands to assume the throne. When he arrived the English army put up no resistance; James fled for France.

In Ireland, the most powerful leader was the earl of Tyrconnel, named lord deputy of Ireland during James' reign. Since 1685 he had been purging the Irish military of Protestants, which resulted in their replacement by Catholics of irregular military quality. In late 1688, before James left England, Tyrconnel had sent a force of Catholic soldiers to garrison Londonderry, replacing one of the few remaining Protestant forces in Ireland, stationed there under Lord Mountjoy. The approach of the ragged Catholic troops stirred up rumors in the town of an upcoming massacre of the almost completely Protestant population. When the troops appeared, a handful of young apprentices (on their own initiative) quickly lowered the city's gates, barring the force's entry. Tyrconnel decided to leave Mountjoy in command for the time being, as news of William's arrival in England had just been received. Mountjoy was soon on his way to England, succeeded by his second in command, Lieutenant Colonel Robert Lundy.

Tyrconnel hoped to take advantage of the "Glorious Revolution" in England to strengthen Ireland's autonomy. While negotiating with the new king, he also sought aid from France. All of this took place in the midst of the Nine Years War, a struggle between Louis XIV's France on one side and a coalition of the Netherlands and the Holy Roman Empire on the other. With William diverted by his new responsibilities in England, Louis decided that he could weaken the continental effort against himself by supporting Tyrconnel's Irish Catholic movement. He prodded a reluctant James into leading a force to Ireland, which landed at Kinsale on the south coast on 12 March 1689.

While awaiting French support, Tyrconnel had been consolidating his hold over all of Ireland, including most of Protestant Ulster in the north. When James arrived from France with 1,200 men, the Catholics escorted him to Dublin, where he assembled a parliament. James proclaimed religious freedom for all who remained loyal to him, then his parliament repealed the Settlement Act of 1652 whereby Englishmen had appropriated Irish lands. They also passed a Bill of Attainder declaring some 2,000 locals to be opponents of the king and thus in forfeit of their lands.

Some 30,000 Protestants fled to the port city of Londonderry, one of the key centers of Protestant English influence. Robert Lundy was still in command of the city's garrison. His exact role in the events is the subject of much debate. He slightly improved the city's defenses but he also negotiated with James' forces. When the Jacobins approached in early April, Lundy fielded an incredibly disorganized force that was quickly driven back into the city after a skirmish at Lifford. When reinforcements arrived from England, Lundy informed them that Londonderry was indefensible and they should return home. When news of that decision leaked out, the citizens decided Lundy was at best untrustworthy and at worst a traitor, so he was expelled. Command of the defense fell to Major Henry Baker and Reverend George Walker, named co-governors. Military command lay in the hands of Colonel Adam Murray, whose arrival with reinforcements prompted Lundy's removal.

When James arrived, believing the city awaited his presence in order to submit, he was met with cries of "No surrender!" from the garrison manning the walls.

Londonderry is situated with the Foyle River on its eastern and northern sides and a bog on its western side through which a causeway offered access. The town was crowded with refugees, but many inexplicably were allowed to flee the city early in the engagement; about 20,000 civilians remained. A force of 7,361 men defended the city. The besieging Jacobite army numbered at first about 4,000, but owing to their open line of communications back to Dublin, reinforcements came and went and the besiegers probably fielded a force of some 12,000 at its greatest strength. They lacked the necessary artillery to reduce the city's walls, possessing only a handful of mortars that maintained a steady bombardment of the city, destroying houses and spreading terror. The defenders possessed twenty cannon, but little is mentioned of any significant damage they may have inflicted on the attackers.

On 21 April Murray sortied from the town to attack an Irish force deploying northward toward the village of Pennyburn. French reinforcements rode to stiffen the Irish, who were badly outnumbered. As Murray's force retreated toward Londonderry, the pursuing cavalry chased them down a lane along which Murray had earlier placed several hundred musketeers. Their ambush virtually wiped out the Jacobin cavalry at one blow, and General Maumont, the French officer commanding the siege, was killed. He was replaced by Colonel John Hamilton.

On the night of 5-6 May, Hamilton ordered a force to seize Windmill Hill, roughly a half-mile southwest of Londonderry. Although they took the hill from a small Protestant force rather easily, 1,000 men sallying from the town dislodged their own force of 3,000 the following day. Murray then strengthened his position by erecting a line of redoubts from the bog (which covered the town's western face) southward to the windmill thence to the Foyle. The remainder of the month passed quietly, but inside Londonderry the food and water situation grew increasingly desperate. Tensions heightened and arguments between officers became frequent. Outside the town, however, the Jacobins were doing little better. The spring had been wet and many were suffering from disease, for the Irish had with them virtually no medical service.

The besiegers, fearful of rumors that re-inforcements were sailing from England, mounted two cannon on the bank of the Foyle north of the town and built a log boom to bar the river to any ships. Forts on both sides of the river protected the boom. With the northern flank covered, Hamilton on 4 June mounted another assault on Windmill Hill, now protected by entrenchments. The attack involved possibly as many as 6,000 men, mixed cavalry, infantry, and grenadiers. The attack was met by virtually the entire garrison and was beaten back, the cavalry losing many horses (there were less human casualties, as the soldiers' cuirasses were effectively bullet-proof). Unable to cross the trenches, the Jacobin army fell back. Casualties among the attackers far outnumbered that of the defenders, and Irish morale began to deteriorate.

A few days later lookouts on the town walls sighted English ships entering Lough Foyle to the northeast. It was for a time only a tantalizing vision, for the relief force's commander, Major General Percy Kirke, hesitated to challenge the boom and artillery blocking the river. Instead, he debarked his 2,000 troops upstream and set up camp. There was no way to establish communications with the garrison, although messengers were dispatched from both town and fleet. None got through, and one (who died trying) carried a message captured by the Jacobins that the city had no more than a week's rations remaining. It was not that bad; the governors had painted a bleak picture in order to motivate Kirke. Still, it was bad. The citizens had for a while eaten well off the horsemeat from the dead cavalry mounts after the second Windmill Hill battle, but by late June they were back to eating dogs, cats, rats, and anything else that could be caught and killed.

Hamilton was about to offer Londonderry rather generous terms when General Conrad de Rosen arrived with word from King James to finish the town off. Rosen rounded up a number of local Irish and herded them in front of the town walls where they would starve unless taken in; the defenders responded by displaying their own prisoners alongside a quickly built gallows in plain sight of the Irish army. Rosen backed down.

In the meantime, Kirke had reloaded his men aboard their ships and sailed around to Lough Swilly to the northwest. This placed him in a position to attack the Jacobin force from the rear. Through the efforts of a young boy messages were now being exchanged with the garrison and Kirke learned that the situation was in reality as desperate as had been described in the earlier lost dispatch. The besiegers were in only slightly better condition. While their food supply was much better, they were losing large numbers to a variety of diseases, including smallpox. James ordered Hamilton to offer terms to the garrison too good to reject, and for a time the two sides negotiated, for in spite of his strong position Kirke would not move without orders from England. In mid-July he received a directive to force the boom and break through to Londonderry. He again embarked his troops and sailed back to Lough Foyle. The merchantman Mountjoy ran hard against the boom, severely damaging it, but foundered in the process. Another ship, the Phoenix, darted past the Irish artillery and sped for the town with fresh food.

The breaking of the boom meant that, with sufficient suppression gunfire from aboard, ships could run the river and relieve the garrison. The Jacobin army fired a few shots at the ships the next day, but they knew they had failed. On 1 August, after 105 days of siege, the Irish army retreated. They had suffered perhaps 8,000 casualties. The defenders had suffered severely as well. Of the 7,000 defenders more than half had died, and the percentage of civilian deaths was approximately the same, primarily from starvation.

Although the battle of the Boyne the following year marked the "official" end of James's attempt at restoration, the defeat at Londonderry was a psychological turning point. It has over the intervening three hundred years become a Protestant landmark in Ireland, and the annual Apprentice Boys parade in the city marks the occasion of the initial Protestant defiance of James' intervention and the establishment of the Protestant ascendancy. Militant Ulstermen use it as a rallying point, citing Lord Macaulay's nineteenth-century account from the History of England: "Five generations have since passed away ... still the Wall of Londonderry is to the Protestants of Ulster what the trophy of Marathon was to the Greeks." Had the Jacobin force captured the city, James could possibly have both consolidated his hold on Ireland and used it as a base to strengthen the concurrent rising in Scotland. Whether he could have defeated William in open combat somewhere in England no one can say, but the challenge to the new ruling house could have been successful; it certainly had a greater chance of succeeding than did Bonnie Prince Charlie's 1745 rising.

The call of "No surrender" from the walls of Londonderry has remained an Irish Protestant battle cry ever since 1689.