Warbeck landed in Ireland in 1491. The conspiracy lasted until 1499.
Warbeck had a plan that involved Charles VIII and Margaret of Burgundy. Henry’s relations with Scotland and France were poor so they could use Warbeck to undermine his position and exert diplomatic pressure to not become anti-French over his wish to annex Brittany.
Warbeck was unable to win large scale support in Ireland but he was welcomed at the French court where he was joined with 100 Yorkist supporters.
The signing of the Treaty of Etaples in 1492 between England and France meant that Warbeck was forced to move to Flanders where he had the support of Margaret. Henry broke off the cloth trade with Burgundy over this.
Warbeck gained support from Maximilian (HolyRomanEmperor) who recognised him as Richard IV. Henry could act without fear of European intervention as Maximilian lacked financial support and France was more concerned with Italy.
Henry found out about the conspiracy due to spy networks so parliament passed a series of attainders against those who implicated in the plot such as Sir William Stanley who was the leading courtier/Lord Chamberlain of Kings household and supported Henry at Bosworth.
Warbeck landed at Deal in England in 1495. Local militia were able to defeat the army without the use of a royal army. Warbeck fled to Ireland where he failed to capture Waterford.
Warbeck was welcomed into Scotland where he planned to marry James IV’s cousin. He provided 1,500 troops to invade Northern counties of England.
Warbeck lacked support in Northern counties so he was forced back to Scotland where James abandoned him as he preferred the offer of marriage between him and Henry’s daughter, Margaret.
Warbeck sailed to England to capitalise on the Cornish rebellion after returning to Ireland in 1497 and finding no support. He was driven from Exeter and Taunton and forced to seek sanctuary.
November1497, Warbeck was persuaded to hand himself in and Henry allowed him to stay in court but he tried to escape with the Earl of Warwick in 1498 so Henry put him in the Tower.