The Church of England refused to bless their engagement, and when Peter was posted to Belgium, Margaret accepted the proposal of photographer Antony Armstrong-Jones.
Princess Margaret and Antony married in 1960, with their wedding making history as the first ever royal wedding to be televised.
Upon their marriage, Antony was bequeathed the title 'Earl of Snowdon'.
The couple went on to have two children: David Albert Charles Armstrong-Jones in 1961
Later on in life, Princess Margaret suffered from many illnesses, including cancer.
It was well known the Princess was fond of smoking cigarettes and even smoked up to 60 a day.
Tragically, on February 9, 2002, Princess Margaret died of complications following a stroke at the age of 71.
Where are Princess Margaret's children now?
Princess Margaret's son David Armstrong-Jones was titled Viscount Linley at birth and is currently 20th in line to the throne.
After studying woodworking in Dorset, David now runs his own furniture company called 'Linley'.
He married Irish noblewoman Serena Alleyne Stanhope (now the current Countess of Snowdon) in 1993 and has two children, Charles Patrick Inigo, the current Viscount Linley, and Lady Margarita Elizabeth Rose.
Margaret's daughter Lady Sarah Chatto, née Armstrong-Jones, is an accomplished painter and the current vice president of the Royal Ballet.
Although she has kept out of the limelight, Lady Sarah is reportedly her aunt Queen Elizabeth's close confidante.
Lady Sarah married her husband Daniel Chatto in 1994 and they share two sons, Samuel David Benedict, and Arthur Robert Nathaniel.