Anne's public role developed within the unsettled succession politics of the later Stuart monarchy. She supported the change of regime in 1688 that displaced her father James II and eventually succeeded William III in March 1702. The death of her surviving son William in 1700 had made the future of the Protestant succession especially urgent. The Act of Settlement of 1701 designated the Hanoverian line after Anne. Her position therefore involved both continuing Stuart identity and the prospect that the dynasty would cease to rule. Personal grief and illness formed important constraints, without making her merely a passive figure at court.

The War of the Spanish Succession dominated most of her reign. Ministers such as Sidney Godolphin and the Duke of Marlborough sustained an alliance against the expansion of French and Bourbon power. Victories including Blenheim and Ramillies strengthened Britain's military reputation, while naval operations and finance supported a global conflict. The war increased taxation, borrowing and political controversy. Anne's appointments and preferences mattered in balancing ministers, though she operated within a system increasingly dependent on Parliament and organized party support.

The Acts of Union in 1707 united England and Scotland as the Kingdom of Great Britain. Negotiation involved succession security, trade, public finance and the distinct religious establishments of the two kingdoms. Anne supported union, but the settlement was enacted by the parliaments and did not erase Scottish law or the Presbyterian church. At court, her friendship with Sarah Churchill deteriorated as personal tensions became entangled with the Whig–Tory struggle. Abigail Masham's growing influence and Anne's preference for the Church of England contributed to the shift toward Robert Harley and Henry St John.

A Tory ministry came to power in 1710 and pursued peace. The Treaty of Utrecht in 1713 recognized important British gains and reduced the threat from France, but its negotiation divided opinion and changed relationships with allies. Anne's declining health intensified disputes about succession and ministerial control. She died in August 1714, and George I inherited under the Protestant settlement. Later portrayals focused on favourites or physical infirmity have often understated her engagement with appointments, religion and policy. Her reign established the united kingdom and advanced the role of party and Parliament.