Limerick is known as the Treaty City because the Treaty of Limerick signed there on the 3rd of October 1691 after the war between William III of England (William of Orange) and his Father in Law King James II.

The Treaty, according to tradition was signed on a stone in the sight of both armies at the Clare end of Thomond Bridge on the 3rd of October 1691.

The stone was for some years resting on the ground opposite its present location, where the old Ennis mail coach left to travel from the Clare end of Thomond Bridge, through Cratloe woods en route to Ennis.

The Treaty stone of Limerick has rested on a plinth since 1865, at the Clare end of Thomond Bridge. The pedestal was erected in May 1865 by John Richard Tinsley, mayor of the city.

The Treaty of Limerick, signed on 3 October 1691, ended the 1689 to 1691 Williamite War in Ireland, a conflict related to the 1688 to 1697 Nine Years' War. It consisted of two separate agreements, one with military terms of surrender, signed by commanders of a French expeditionary force and Irish Jacobites loyal to the exiled James II. Baron de Ginkell, leader of government forces in Ireland, signed on behalf of William III and his wife Mary II. It allowed Jacobite units to be transported to France, the diaspora known as the Flight of the Wild Geese.

The other set out conditions for those who remained, including guarantees of religious freedom for Catholics, and retention of property for those who remained in Ireland. Many were subsequently altered, or ignored, establishing the Protestant Ascendancy that dominated Ireland until 1916.