At what should have been the crowning moment of his political career, Lyndon B. Johnson, who died on 22 January, 1973, famously told a joint session of the American Congress, “All I have I would gladly have given not to be standing here today.”

It was November 1963 and Mr Johnson had just become President, but he was addressing Congress in the aftermath of President John F. Kennedy’s assassination — a uniquely bleak and directionless moment in US history.

He took it upon himself to push through a programme of civil rights legislation aimed at bringing social justice to all groups in American society and making a nation feel proud of itself once more.

But despite his landmark reforms and his unnerving ability to twist the arms of opponents and allies alike at home, it was events on the other side of the world that brought a sudden and unexpected end to his political career.

Lyndon Baines Johnson was born on 27 August, 1908 in Stonewall, Texas , and after a stint as a school teacher, he became a congressman’s secretary before securing election himself as a “New Deal” Democrat in 1937.

He was decorated for services in the navy after Pearl Harbor , becoming a senator in 1948 and majority leader of the Senate seven years later.

Having unsuccessfully contested the Democratic nomination, he became Vice-President under John F. Kennedy in 1960.

Three years later, he was to achieve his political ambition: on 22 November 1963, he was sworn in as President of the United States of America — in the most tragic of circumstances.

Mr Johnson’s own presidential career was characterised by the civil rights agenda, economic and social policies under his signature programme, the “Great Society”, and Vietnam .

In 1964, Mr Johnson was returned to office in a landslide election victory, and within months, he had signed the Civil Rights Act and a year later the Voting Rights Act, both giving limited but significant improvements to black Americans.

In spite of that legislation, US cities continued to burn throughout Mr Johnson’s presidency, but by 1965, he had turned his policies to education for the young and the Medicare health insurance programme for the elderly.

His stance on Vietnam pleased neither pro nor anti-war campaigners, but after the Tet offensive and mounting casualties in 1968, Mr Johnson became the story, with student, hippie and Black Panther protests focused on the President himself to such an extent that he was even advised not to attend his own party’s annual convention.

Despite being entitled to seek re-election, he decided to retire from politics rather than fight for a second term in 1968, and he returned to Texas where he wrote his autobiography The Vantage Point , published in 1971, and inaugurated his presidential library at the university of Austin .

Two years later, aged 64, he died of a heart attack brought on by years of heavy smoking and stress, finally succumbing to an illness that may have influenced his decision to restrict his presidency to just one full term.

A career politician, in a little over 30 years Mr Johnson went from congressman’s secretary to former US President, and although he took centre stage when Mr Kennedy's dream of a new Camelot turned into a nightmare, he was already renowned as one of the expert politicians of his generation.

Despite accusations of vanity, chicanery and malevolence, in the turmoil after Mr Kennedy’s death, Johnson came into his own, prompting TIME magazine to say, “He somehow reached out and comprehended that incredible problem, surrounded it and mastered all the details. In the short view, at least, he produced a near miracle in a storm center of anguish.”