This battle took place on 21st September 1795 outside Loughgall Co Armagh, by some accounts it was little more than a skirmish, it was one of a number of violent sectarian conflicts which flared up sporadically on the edge of the Ulster Plantation area. Accounts of the loss of life vary from 4 to 30 on the Catholic side, while there appears to have been no Protestant fatalities.

In the years leading up to the battle The United Irishmen had sought to encourage solidarity between the Protestant and Catholic working class, naturally this was not in the interest of the ruling class.

The Orange Order was formed after The battle of the Diamond largely from a core of the Peep O Day Boys, which ironically was initially formed in 1784 to combat landlord oppression, the cottage were it was formed stands in the village of Loughgall and is now a museum.

Within a short period of time members of the Protestant landowning class were to be found as county grand masters and at the head of the order, in effect they had what might be described as a private army at their disposal. A position they utilised via the ballot box and other means to maintain their privileged position until comparatively recently. In effect The Orange Order became an instrument of class rule.

Comprehensive account of the causes and effects of The Battle of the Diamond on Wikipedia