ROYALTY IS A high-risk profession, as the lifetime of Louis Mountbatten testified. Related to nearly all the royal houses of Europe, his family story contains dozens of personal tragedies. As an adolescent, he witnessed the wrecking of his father's naval career by international politics, and the massacre of his Russian relatives -- including the girl he planned to marry -- by the Bolesheviks. Thereafter, a long succession of cousins, in Spain, Yugoslavia, Greece and elsewhere, lost their thrones and ended up on the beach in Esroil. He himself, at the age of 79, was blown to pieces, with other members of his family, by Irish terrorists.

"For an Admiral of the Fleet to be killed instantly, at sea, by his countries enemies, is not the worst way to go," writes John Terraine, in the epilouge to his book based on the television series about Mountbatten's career. Certainly, Mountbatten had always loved drama, excitment, dressing up in uniforms, ceremonies (he planned his own funeral in enormous detail). Above all, he loved speed. "His normal' speed', at the age of sixty-seven,' Terraine writes, "was I should say about three times the highest speed I have ever been able to achieve at any time in my life." Richard Hough, in his more formal biography, puts it thus: "Speed -- in reaching decisions, speed in all his activities, from polo to driving cars, destroyers and speedboats -- was essential to his style of living."

This extraordinary celebrity, which of course, as Terraine points out, rested on "an unusual degree of energy," enabled Mountbatten to cram several careers into one. Hough's narrative makes it clear that he was a superb destroyer commander in action. He was also an excellent planner, able to operate as part of a team, whether engaged in a large-scale land-sea invasion or making a TV movie (Terraine gives some illuminating glimpses here). Like Dwight Eisenhower, he had the gift of cajoling men of very differnt temperaments into working together. This explains his success both as a combined-operations commander and, later, as professional head of the British Navy, NATO commander and defense chief of staff.

Unusually for a royal, he was always open to new ideas. More than any other naval officer of his generation, he grasped the need to understand and incorportate electronic technology. He was also one of the first members of the English establishment to accept decolonization, which made him an apt choice as Britian's last Indian viceroy, charged with the task of getting out gracefully.

Because he had an open mind, Mountbatten was never arrogant. He fault was vanity. He loved to talk about himself, though seldom tediously. Terraine's book allows him to take the floor most of the time, and the result is a liveliness which Hough's biography lacks, though it contains a great deal more information. Oddly enough, Terraine points out, he seldom boasted of his more serious exploits. Instead, he claimed to be the first man to cure lameness in horses, the first to wear zips instead of buttons on his flies, to wear socks with built-in garters, which he designed himself. He said he had invented a new kind of paint and "tracking headlights which follow a cars front-wheels round corners." These claims, on investigation, usually turned out to be true.

Yet though Mountbatten seems so essentially a public figure, his real genius was for family life, of the royal, extended-family variety which reaches across frontiers and continents. As a penniless royal he did the right thing by marrying an heiress, granddaughter of the Edwardin banking tycoon, Sir Ernest Cassel. Edwina Mountbatten was also a great beauty and a clever, resourceful woman: together they made a formidable couple. Their life is touchingly described in a short book by Charles Smith, in turn footman, valet and butler in the household. This is no book for radicals: "People should never marry out of their station, otherwise discontent will soon emerge. Lord and Lady Louis were prefectly matched." Nor is it one for those who like malicious gossip: It ends: "No man is a hero to his valet? What mockery Lord Louis made of that saying." The book is naive, honely, and I should say truthful.

The Mountbattens had no son: but a surrogate appeared in the shape of his eldest sister's boy, Prince Philip of Greece. Like Mountbatten at the same age, Philip had brains, energy, royal blood, good looks but no money. He needed an heiress, and the King of England had one. Mountbatten is generally credited with bringing Philip and Elizabeth together: in the words of Philip's biograhper, Denia Judd, "Uncle Dickie," as he was known in the British royal family, "campaigned with skilful persistence on Philip's behalf."

Mountbatten's aims were altrusic as well as personal. He felt that, these days, a royal family cannot afford to make even one big mistake, and during the abdication crisis of 1936 he had seen the entire royal circus nearly leave the road. In Philip he felt he had found (to use an English cricketing term) "a safe pair of hands" -- enterprising but level-headed, open to new ideas but a traditionalist at heart, brainy but not clever-clever, with the strict interior discipline which marks true professional royalty. Judd's well-researched biography shows that Mountbatten was a good judge. Phillip has had some difficult patches, especially with the press, but his is undoubtedly a success story in a supremely difficult role, and Judd tells it well.

For Mountbatten, the marriage proved a masterstroke in his general strategy for the British royal family. It gave the young Queen a dependable husband. It allowed Mountbatten to assume the role of elder statesman of the family. And, in due course, it meant he could instill into the future king, Prince Charles, the principles of his survival plan. What are these principles? Broadly, to make small but continuous updatings of the substance of royal work, while mintaining absolute continuity of the glamorous external ceremonial. The formula involves the stealthy pouring of new wine into old bottles, if you like; but it seems to work. When Uncle Dickie made his spectacular exit, he left the family firm in remarkably good shape.