Henry was threatened several times during his reign all of varying seriousness.
The pretenders fist threatened Henry in 1487, the first being Lambert Simnel. Henry was still unstable after his usurpation of the throne and due to on going threats security remained an issue for most of his reign. In Ireland, Yorkist influence was still strong for Henry and this was a massive threat to Henry. Henry was already concerned about the security of his monarchy due to the Yorkshire rising led by Lovell and the Stamford threats.
This however turned out to be less then a formidable threat for Henry only alarming him and highlighting the instability of his crown. It is thought that the lack of serious Yorkist claimants led to the creation of pretenders. Lambert Simnel arrived in Ireland in 1487 claiming to be the Earl of Warwick and quickly gathered widespread support. Ireland was still very sympathetic towards the Yorkists and Kildare Henry’s Lord Deputy, was anxious to hold independence and was more then willing to support Simnel.
Kildare betrayed Henry this illustrated how deep Simnel’s threat had become. The threat peaked at Simnel’s coronation in Dublin, at this point Henry must have undoubtedly realised the extent of the threat. Although Simnel’s imposture held little plausibility for a time he gained a shocking amount of support, especially from foreign powers. At this stage Simnel was an acute threat to Henry, he could not estimate with enough precision, what extent of support would be produced for Simnel. Henry acted quickly to meet the military threat and fortunately for Henry, Simnel had failed to gather enough of the required support.
He invaded too fast and therefore didn’t gain any support from the north, Simnel and his followers were defeated at the Battle of Stoke. Looking back on Simnel’s threat it is fair to say that a barely credible claimant managed to gather a strong following from disaffected parts of Henry’s kingdom. The second Pretender, Perkin Warbeck first posed as a threat to Henry in 1491, here he claimed to be Richard of York, the youngest son of Edward IV. Warbeck threatened the monarchy for 8 years, at times becoming a key threat for Henry and at others merely insignificant. Warbeck was a constant threat to Henry, unlike Simnel due to his hesitance to become involved in battles.
Although at points during the 8 years Warbeck was simply a nuisance in foreign affairs and therefore foreign policy at times he presented a large problem for Henry. Perhaps most surprising was the amount of support for Warbeck obtained from foreign powers, however although much more lengthy then Simnels threat it did not carry the same force and was much more entwined in European affairs. Henry was first threatened by Warbeck in Ireland however this is was predominantly inconsequential. He gained some support in Ireland but Kildare took care not to get involved however did not attempt to deal with the problem. Henry sent a small army to Ireland and Warbeck fled to France.
Margaret of Burgundy gave the first amount of significant support to Warbeck, however Henry was able to act quickly enough and a trade war began between England and Burgundy. Burgundy were preoccupied with Italian affairs and so could not support Warbeck immediately, this gave Henry time. In 1495 Sir William Stanley and a number of other leading government figures were accused and executed, Warbeck had become a key threat to Henry as he had infiltrated and gained support from his own government and some of his most trusted associates. Warbeck landed on English soil in July 1495, this would have been seen as a immense threat to Henry however in practicality Warbeck had roused little support and presented relatively no military threat. This was nevertheless difficult to predict for Henry so at the time the threat was still an intense one. Warbeck was quickly forced to sail to north.
Warbeck moved to Scotland to gather further support, James IV offered Warbeck money, Lady Gordon in marriage and preparation began for war with England. At this time it was a Warbeck was a great threat to Henry not only was he having to deal with Warbeck in the North but also an uprising in Cornwall. Although the Cornish rising was not over dynastic issues, this seriously aggravated the threat for Henry. Henry was unaware of the extent of the Scottish threat and feared the worst, in reality it was a feeble effort however Henry could not foresee these details, perhaps more worrying at the time was the threat of the Cornish rising.
It must have shocked Henry to hear that several thousand rebels had marched unchallenged from Cornwall to Blackheath, making Henry unsure who he could call on in times of difficulty. The sheer fact that they managed to march unopposed across England was a threat in itself but marching directly on the capital and adding to the problem Warbeck and James IV made it the largest threat to Henry during his reign. Two months later the Scots invaded again and Henry prepared to retaliate by land and sea while Warbeck struggled to gather support in Ireland. Warbeck landed in Cornwall hoping to turn the Cornish rising to his advantage although he gathered some support he failed to take Exeter while meanwhile the Scots withdrew at Surrey.
Warbeck fled but was captured and imprisoned in the Tower. Both Simnel and Warbeck presented major threats towards Henry during the years 1485 -1499. The lack of true Yorkist claimants to the throne encouraged the uprising of pretenders, half the problem with pretenders was the fact that people believed it. Although Simnel and Warbeck were highly implausible they still gathered much support however Henry managed to quickly contest their every move.
At the time Henry was unable to predict with any certainty the extent of any threat against him and therefore all threats were more serious to Henry. Although at the time major threats for Henry with hindsight many of Simnel and Warbecks threats were pathetic and lacking in support. Each threat nonetheless had its own level of seriousness, the most serious perhaps being Warbeck and James IV’s threat together with the crucially timed Cornwall rising in 1485. What made all the threats more menacing was the intervention of foreign powers. In conclusion it is with out doubt that an immense threat was presented to Henry in the years 1485 onwards by the pretenders.