Queen Elizabeth II is the longest-reigning monarch in British history.

She’s a beloved-yet-enigmatic figure, whose belief in duty and tradition has seen her through 12 prime ministers, several family scandals and enormous global changes. The ambitious Netflix series “The Crown” attempts, in meticulous detail and sumptuous surroundings, to capture the early years of her reign, when, in 1952 at the age of 25, she became the ruler of the monarchy and the Church of England.

Claire Foy (“Wolf Hall”) and Matt Smith (“Dr. Who”) play Princess Elizabeth and her young husband, Prince Philip of Greece, whose future is decided for them when King George VI (Jared Harris, so memorable as Lane Pryce on “Mad Men”) dies of lung cancer. George, nicknamed Bertie, picked up where his brother, Edward VIII (Alex Jennings), left off when he abdicated the crown rather than give up his lover, Wallis Simpson (Lia Williams), a divorcée. George earned the love of the British people, as Harris says, “against all expectations. The second World War broke out and gave him an opportunity to define the monarchy to his people for that period.”

“The Crown” was created by Peter Morgan, who’s made a career writing about Elizabeth II, both in the Oscar-winning film “The Queen” and in the play “The Audience.” He uses London locales such as Pall Mall’s Lancaster House as a substitute for the Buckingham Palace state rooms, but the series really flexes its muscle when it delves into the power plays that forced the queen to keep her own counsel.

After her father dies, Elizabeth receives a rather direct letter from her formidable grandmother, Queen Mary (a devastating Eileen Atkins). “Your people will need your strength and leadership,” she says in a voiceover. “I have seen three great monarchies brought down through failure to separate indulgence from duty.”

The show pits Elizabeth against some obvious adversaries — an elderly Winston Churchill (John Lithgow), the prime minister who’s nearly shown the door when he acts too late on a public health crisis. “He’s lying to her,” Foy says. “She can’t go into the street and see what’s actually going on. She’s only taught to believe what they tell her to believe.

“Everybody’s got an agenda here.”

Some of her battles are deeply personal, and wound her loved ones, particularly her husband, who is not allowed to keep the Mountbatten surname when the Cabinet decides “Windsor” would be better. Worse, Elizabeth alienates her younger sister, party girl Princess Margaret (Vanessa Kirby), when she forbids her to marry her lover, Battle of Britain hero Group Capt. Peter Townsend (Ben Miles), who served as an equerry to her father. Townsend was divorced — and as supreme governor of the Church of England, which forbade divorce, Elizabeth must enforce the rules.

“Margaret’s spirit is crushed,” says Kirby. “And her heart is hardened. At the end of Episode 10, she says, ‘I will never forgive [Elizabeth].’ Townsend was her great love.”

Besides the sterling production values and superior performances, “The Crown” draws much of its appeal from the fact that Elizabeth II is still ruling, a modern amazement. Politicians and fame seekers such as Princess Diana come and go, yet Elizabeth II has outlasted and them all, just by doing her job.

Working on the show changed Kirby’s view of the monarch.

“I have to say I wasn’t quite sure if she was [still] relevant,” Kirby says. “But doing the series, you actually see this woman having no choice. The life she thought she could have [was] completely taken away from her. And doing it with great dignity, quiet resolve and silence. I’m so glad my judgment has been so completely turned on its head.”

“The Crown” Series available Friday on Netflix