On May 1, 1707, the parliaments of England and Scotland formally united under the Acts of Union, creating the Kingdom of Great Britain with a single parliament sitting at Westminster. The union followed years of negotiation and economic pressure, notably the disastrous Scottish Darien scheme, which had left Scotland's finances in ruin. Scotland retained its own legal system and Presbyterian church, but surrendered its independent parliament.
Scotland entered the union from a position of economic weakness. The catastrophic failure of the Darien scheme in the 1690s, an attempt to establish a Scottish colony in Panama, had drained a substantial share of the nation's liquid capital and left its landed elite desperate for financial rescue.
England, meanwhile, wanted assurance that its northern neighbor would not ally with France or restore a Catholic Stuart monarch to the throne, especially with the War of Spanish Succession raging across Europe. Negotiators on both sides hammered out a treaty offering Scotland financial compensation and continued protection of its distinct legal and religious institutions.
When the Acts took effect on May 1, 1707, the flags of St. George and St. Andrew were combined into the Union Jack, and a single Parliament of Great Britain replaced the separate legislatures in Edinburgh and Westminster. The union proved deeply unpopular among ordinary Scots at the time, sparking riots in Edinburgh, but it laid the political foundation for an eventual global empire, and the debate over Scottish independence it set in motion continues to reverberate in British politics three centuries later.