What major event happened when Queen Elizabeth the second was alive?

During Queen Elizabeth II's reign, one of the most significant events was the 9/11 terrorist attacks in the United States on September 11, 2001. This event had a profound global impact, leading to widespread changes in security policies and international relations. Additionally, her reign saw the United Kingdom's involvement in various conflicts, including the wars in Iraq and Afghanistan, and significant social changes, such as the legalization of same-sex marriage in the UK.