Immortal Seven

The Invitation to William was a letter sent by seven notable Englishmen, later named the Immortal Seven, to William III, Prince of Orange, received by him on 30 June 1688 (Julian calendar, 10 July Gregorian calendar). In England a Catholic male heir to the throne, James Francis Edward Stuart, had been born, and the letter asked William to force the ruling king, his uncle and father-in-law James II of England, by military intervention to make William's Protestant wife Mary, James's eldest daughter, heir, alleging that the newborn Prince of Wales was an impostor.

The letter informed William that if he were to land in England with a small army, the signatories and their allies would rise up and support him. The Invitation briefly rehashed the grievances against King James. It claimed that the king's son was supposititious (fraudulently substituted) and that the English people generally believed him to be so. The present consensus is that he was almost certainly their real son. It deplored that William had sent a letter to James congratulating him for the birth of his son, and offered some brief strategy on the logistics of the proposed landing of troops. It was carried to William in The Hague by Rear Admiral Arthur Herbert (the later Lord Torrington) disguised as a common sailor, and identified by a secret code.

The invitation caused William to carry out his existing plans to land with a large Dutch army, culminating in the Glorious Revolution during which James was deposed and replaced by William and Mary as joint rulers. William and Mary had previously asked for such an invitation when William started to assemble an invasion force in April of that year. This request was done through secret correspondence that had been taking place since April 1687, between them and several leading English politicians, regarding how best to counter the pro-Catholic policies of James. William later justified his invasion by the fact that he was invited, which helped to disguise the military, cultural and political impact that the Dutch regime had on England at a time his reign was unpopular and he feared a popular uprising.

...
Wikipedia