Fifty years ago today, US civil rights leader Martin Luther King Jr was assassinated in Memphis, Tennessee.

Here are the key dates and quotes from the pastor, Nobel Peace Prize winner and preacher of non-violence:

15 January 1929: Dr King is born in Atlanta in the southern state of Georgia.

18 June 1953: He marries Coretta Scott and they go on to have four children.

December 1955: A pastor at the Baptist Church in Montgomery, Alabama, Dr King takes the lead of a year-long boycott against racial segregation on local buses. It results in an end to such segregation and earns him a national profile.

"Yes, if you want to say that I was a drum major, say that I was a drum major for justice. Say that I was a drum major for peace. I was a drum major for righteousness. And all of the other shallow things will not matter."

April 1963: Arrested after demonstrations against racial segregation, Dr King writes his famous 'Letter From a Birmingham Jail' in which he outlines his non-violent resistance to racism.

"I believe that unarmed truth and unconditional love will have the final word in reality. This is why right, temporarily defeated, is stronger than evil triumphant."

August 1963: Dr King pronounces his inspiring "I Have a Dream" speech to about 250,000 people at the March on Washington for Jobs and Freedom.

"I have a dream that my four little children will one day live in a nation where they will not be judged by the colour of their skin but by the content of their character."

October 1964: Aged 35, he becomes the youngest Nobel Peace Prize winner at the time for his non-violent resistance.

Martin Luther King receives the Nobel Peace Prize in Oslo, Norway

1966: Dr King moves to the slums of Chicago to extend the civil rights movement into the north of the country.

1967: He denounces the war in Vietnam and expands his campaign against poverty in the United States.

"I oppose the war in Vietnam because I love America. I speak out against this war, not in anger, but with anxiety and sorrow in my heart, and, above all, with a passionate desire to see our beloved country stand as the moral example of the world. I speak out against this war because I am disappointed with America. And there can be no great disappointment where there is not great love."

Dr Benjamin Spock & Dr Martin Luther King lead 5,000 marchers in Chicago protesting against the Vietnam War

4 April 1968: Dr King is assassinated at age 39 by James Earl Ray as he is standing on a motel balcony in Memphis, Tennessee.

The Lorraine Motel where Dr King was shot dead

"The ultimate measure of a man is not where he stands in moments of convenience and comfort, but where he stands in moments of challenge and controversy." 

- King's 1963 book 'Strength to Love'