To take off the top of anything, comes "crop" meaning a closely cut head of hair, found in the name "croppy" given to the Roundheads at the time of the Great Rebellion, to the Catholics in Ireland in 1688 by the Orangemen, probably with reference to the priests' tonsures, and to the Irish rebels of 1798, who cut their hair short in imitation of the French revolutionaries.
Lawless Protestant associations, called Peep o' Day Boys, terrorized the north and were the progenitors of the Orangemen (1789).
The Ulster Orangemen resolved to get in the crops, and to go in armed force sufficient for the purpose.
The rebellion put an end to the growing reconciliation between Roman Catholics and Protestants; religious passions were now violently inflamed, and the Orangemen and Catholics divided the island into two hostile factions.
It is a curious circumstance, in view of the subsequent history of Irish politics, that it was from the Protestant Established Church, and particularly from the Orangemen, that the bitterest opposition to the union proceeded; a,nd that the proposal found support chiefly among the Roman Catholic clergy and especially the bishops, while in no part of Ireland was it received with more favour than in the city of Cork.