The longest reigning British monarch is Queen Elizabeth II. She ascended to the throne on February 6, 1952, and reigned for over 70 years until her passing on September 8, 2022. Her reign witnessed significant changes in British society and the Commonwealth, including decolonization, advancements in technology, and shifts in social attitudes. Queen Elizabeth II was known for her sense of duty and commitment to public service, having celebrated numerous milestones, including her Silver, Golden, and Platinum Jubilees. Her legacy emphasizes stability, continuity, and a dedication to her role as a constitutional monarch.