Some kind of stability was established with the arrival of the Normans at the end of the twelfth century. They expanded and fortified the town; King John arriving in 1210 to inaugurate King John's Castle, one of his finest. High walls were built that were now to keep the Gaels out, and because of this exile the first suburb across the Abbey River began to grow into Irishtown . There was trouble again with the visits of Edward Bruce in the fourteenth century; but the real emasculation of the city began with the onslaught of Cromwell's forces under the command of his son-in-law, Ireton, in the late 1640s. It was concluded when the city rallied to the Jacobite cause in 1689.

Following James II defeat at the Battle of the Boyne in 1690, most of his supporters surrendered quickly - except for the ones at Limerick. As the Williamites advanced, the Jacobite forces within Limerick castle resolved to fight it out under the command of their Irish champion Patrick Sarsfield , Earl of Lucan and second in overall command of the Jacobite army. Although the walls of a medieval castle had little hope of withstanding seventeenth-century artillery (one of James's French generals declared that they would not stand up to a bombardment of apples), Sarsfield gained time by sneaking out, with five hundred of his troops, for a surprise night attack on William's supply train. He succeeded in totally destroying the munitions, while William sat waiting for them in front of the castle walls. However, when the Williamites returned the following year, Sarsfield could finally hold out no longer, and he surrendered on October 3, 1691, to the terms of a treaty that's so sore an historical point that it's still stuck in the minds of most Limerick people today.

The treaty terms were divided into military and civil articles. Militarily, Jacobite were allowed to sail to France, which most of them did, along with Sarsfield himself (he died on the battlefield at Landon in Belgium, two years later); the civil agreement promised Catholics the religious and property rights they'd once had under Charles II. Within a couple of months the English reneged on this part of the treaty, and instead enforced extreme anti-Catholic measures . There followed civil unrest on such a scale that the city gates were locked every night for the next sixty years, and the betrayal has never been forgotten - it alone may explain the roots of today's element of Republican support in the city. The concordat was supposedly signed upon the Treaty Stone that rests on a plinth at the western end of Thomond Bridge. For many years, although this was used as a stepping stone for mounting horses, small pieces continued to be gouged out as souvenirs; one fragment set into a ring is said to have fetched A?1000 in the US.

It was not a promising start for the modern city, and there are those who claim that festering resentment has stunted Limerick's growth ever since. Being also lumbered with a geographical setting that gives it the Irish name luimneach ("a barren spot of land") has not helped. One redeeming factor has to lie in its humour; how else could its corporate motto read An ancient city well studied in the arts of war .