Prince Philip has died at the age of 99, Buckingham Palace has confirmed.
The Palace announced the sad news in a statement to Insider on Friday morning, April 9.
It read: "It is with deep sorrow that Her Majesty The Queen announces the death of her beloved husband, His Royal Highness The Prince Philip, Duke of Edinburgh.
"His Royal Highness passed away peacefully this morning at Windsor Castle."
The news comes after the Duke was released from St Bartholomew's, where he was transferred after spending 13 nights at a London hospital on March 1.
Buckingham Palace said in a statement cited by the BBC that he was being treated for an infection and receiving treatment for a pre-existing heart condition.
At the time of his admission, the Duke was said to be responding to treatment and "remains comfortable".
He was initially admitted to King Edward VII's hospital on February 16 as a precautionary measure after feeling unwell, with a palace aide stating that he walked into the hospital unaided.
While the exact reason for Prince Philip's initial hospital stay was not disclosed, it was stated not to be caused by Covid-19.
The BBC reports that both he and the Queen were vaccinated in January.
The announcement comes after years of declining health for the Duke. In 2011, following chest pains, he was treated for a blocked coronary artery at Christmas while the Royal Family gathered to celebrate the event.
A year later, he was forced to miss the Queen's diamond jubilee concert after he was hospitalized by a bladder infection.
Prince Philip married Queen Elizabeth in 1947. After fighting in World War Two, he renounced his own royalty to marry her. The pair had four children together: Charles, Prince of Wales, Anne, Princess Royal, Prince Andrew, Duke of York, Prince Edward, Earl of Wessex - all of whom survive their father.
As per The Greater London Lieutenancy, the United Kingdom has entered into a national period of mourning. All flags apart from the Royal Standard will be lowered to half-mast.
In his role as prince consort, Philip was the longest-serving male member of the Royal Family.