Four days of celebrations honouring Queen Elizabeth II’s 70 years on the throne kicked off Thursday with a display of British military traditions stretching from the days of horse and cannon to the jet age.

Queen Elizabeth II, Kate, Duchess of Cambridge, Prince Louis, Princess Charlotte, Prince George, and Prince William watch from the balcony of Buckingham Place

Thousands of people, some of whom camped overnight, lined the parade route — many of them sporting Union Jack flags, party hats or plastic tiaras. Carly Martin, who caught a late-night bus from south London with her daughter, said she had come “to make memories.”

Members of the Household Division Foot Guards’ bands march past Buckingham Palace during the Trooping the Colour in London

The 96-year-old queen is Britain’s longest-reigning monarch and the first to reach the milestone of seven decades on the throne. Elizabeth smiled broadly Thursday as she spoke with her great-grandchildren and looked up as the British military aircraft roared over the palace. The six-minute display included Typhoon jets flying in a formation spelling out the number “70.”

The Kings troop of the royal horse artillery ride down the Mall on their way to fire ceremonial gun in London

The jubilee is being commemorated with a four-day holiday weekend. The celebration of Elizabeth’s reign includes a service of thanksgiving on Friday at St. Paul’s Cathedral in London, a concert at Buckingham Palace on Saturday and a pageant staged by thousands of performers drawn from schools and community groups around the country on Sunday. Thousands of street parties are planned around the country, repeating a tradition that began with the queen’s coronation in 1953.

The Royal Regiment of New Zealand Artillery, using four 25-pounder guns, react during their 21-gun salute at Point Jerningham

The jubilee is giving many people — even those often indifferent to the monarchy — a chance to reflect on the state of the nation and the huge changes that have taken place during her reign. Former Prime Minister John Major — one of the 14 prime ministers of the queen’s reign — said the monarch’s stoic presence had helped steer the country over the decades.