The Battle of the Diamond was a planned confrontation between the Catholic Defenders and the Protestant Peep o' Day Boys that took place on 21 September 1795 near Loughgall, County Armagh, Ireland.

The Diamond, which was a predominantly Protestant area, is a minor crossroads in County Armagh, lying almost half-way between Loughgall and Portadown.

[4] Catholic Bernard Coile, from Lurgan, County Armagh, who had risen to become a merchant in the linen industry, called upon the local two parishes to agree to a non-aggression pact.

[4] The Peep o' Day Boys are cited in three accounts of the battle as possessing Volunteer muskets, with additional weapons provided by local squires.

[4] One account, by Charles Teeling, who had given up hopes of being a mediator, stated that on his return to Lisburn, County Down, he saw re-formed Volunteer corps with all of their equipment heading for The Diamond.

[4] The numbers had increased so much that by Friday 18 September 1795, a local magistrate, Captain Joseph Atkinson, who lived about a mile north of The Diamond, called for a peace conference between four Protestant landowners and three Catholic priests.

[4] Some Defender reinforcements from County Tyrone however made it to The Diamond and appear to have encouraged their comrades to become "determined to fight",[2] and a decision seems to have been taken that night to advance the next day.

[4] Blacker claims "a large body of 'Defenders' not belonging to the County of Armagh, but assembled from Monaghan, Louth and I believe Cavan and Tyrone came down and were disappointed at finding a truce of this kind made, were determined not to go home without something to repay them for the trouble of their march".

[8] On the morning of 21 September, the Defenders, numbering around 300, made their way downhill from their base, occupying Dan Winter's homestead, which lay to the north-west of The Diamond and directly in their line of advance.

[4] News of this advance reached the departing Peep o' Day Boys who quickly reformed at the brow of the hill where they had made their camp.

[4] The shooting began again in earnest,[4] and after Atkinson gave his weapon and powder to the Peep o' Day Boys, he rode to Charlemont Garrison for troops to quell the trouble.

[5][6] In a sign that tension over the linen trade was still a burning issue, 'Wreckers' continued the Peep o' Day Boys strategy of smashing looms and tearing webs in Catholic homes to eliminate competition.