LONDON — Guns fired, bells tolled and mourning crowds greeted King Charles III as he led Britain into an uncertain new era Friday.

The country entered a lengthy period of national mourning after Queen Elizabeth II’s death, confronting life without its figurehead of 70 years while already troubled by economic crisis and its latest bout of political upheaval.

Follow NBC News’ live coverage here.

The longest-serving heir to the throne, Charles formally addressed the nation and the Commonwealth for the first time as king in a prerecorded address from Buckingham Palace’s Blue Drawing Room.

He paid a moving tribute to his mother’s “life well lived” and vowed to renew her “promise of lifelong service.”

Charles also gave a nod to his own children, announcing that Prince William would take on his former title as the Prince of Wales and saying he wanted “to express my love for Harry and Meghan as they continue to build their lives overseas.”

The new king ended on a personal note: “And to my darling mama, as you begin your last great journey to join my dear late papa, I want simply to say this: thank you. Thank you for your love and devotion to our family and to the family of nations you have served so diligently all these years. May ‘flights of angels sing thee to thy rest.’”

Earlier in the day, the new monarch was greeted by cheers and cries of “God save the King!” from a waiting crowd as he returned to the palace to assume his birthright at the age of 73. He shook hands and took time to observe some of the many floral tributes left in honor of his mother when he arrived at Buckingham Palace shortly after 2 p.m. local time (9 a.m. ET).

Sept. 9, 202202:48

Charles traveled to London from Balmoral, the Scottish castle where the royal family rushed to be by the queen’s side in her final moments.

Mourners had been gathering outside the palace to lay flowers and to witness history since early morning as a well-rehearsed plan for how the nation will bid farewell to one monarch and welcome another swung into action.

With typical order and correctness, Buckingham Palace issued detailed advice Friday morning.

Julie Masters, 57, from Sussex in southern England, said she was the first person to shake the hand of the new king. She had been waiting with hundreds of others, pressed up against the police barriers.

“It’s not really sunk in,” she said. “He said, ‘Thanks for coming.’”

Margaret Walker, from Wokingham, 40 miles west of London, is 95 years old, just one year younger than the queen. She said: “Charles and Camilla shook my hand and I shan’t wash them again!”

Sept. 9, 202204:13

Gun salutes at nearby Hyde Park and at the Tower of London fired 96 rounds — one for each year of Elizabeth’s life. Flags on official buildings are flying at half-staff. The bells at St. Paul’s Cathedral and Westminster Abbey rang out at noon (7 a.m. ET), echoed by church bells across the country.

The queen’s death Thursday at the age of 96, shortly after doctors placed her under medical supervision, came as little shock given her age and recent health issues. But with the country facing unprecedented economic hardship due to spiraling energy costs and inflation, her absence may be felt even more keenly as Britain confronts a crisis without her for the first time in seven decades.

As French President Emmanuel Macron put it in one of the dozens of tributes from world leaders, she represented “through the fluctuations and turmoil of politics, a permanence with the scent of eternity.”