On 9 April 2021, Prince Philip, Duke of Edinburgh, the husband of Queen Elizabeth II of the United Kingdom and the other Commonwealth realms, and the longest-serving royal consort in history, died of old age at Windsor Castle at the age of 99.
The death of the Duke set in motion Operation Forth Bridge, a plan detailing procedures including the dissemination of information, national mourning, and his funeral. The Duke had indicated wishes for a smaller funeral, though amendments were still made to the plan to bring his service in line with COVID-19 regulations, including quarantine for members of the Duke's family travelling from abroad. His funeral took place on 17 April 2021.
Representatives of nations and groups around the world sent condolences to Queen Elizabeth, the royal family, and citizens of the Commonwealth. Flowers and messages of condolence were left by the public at Buckingham Palace and Windsor Castle, with members of the royal family publicly paying tribute to the Duke in the days after his death.
A thanksgiving service attended by politicians and foreign royalty was held at Westminster Abbey on 29 March 2022, which included elements that could not be implemented in the funeral ceremony due to COVID-19 restrictions.
Health issues and death.
Prince Philip, Duke of Edinburgh had several hospital stays in the years leading up to his death. In 2012, he was admitted to hospital with a bladder infection. He had exploratory surgery on his abdomen in June 2013, and he underwent hip replacement surgery in April 2018. 
On 16 February 2021, the Duke was admitted to King Edward VII's Hospital as a precautionary measure after feeling unwell. On 1 March, the Duke was transferred to St Bartholomew's Hospital and two days later, he underwent a successful procedure for his existing heart condition. On 5 March, he was transferred back to King Edward's, and on 16 March, he was discharged and returned to Windsor Castle.
Three weeks after his return from hospital, his death was announced by the royal family at noon BST on 9 April 2021, with the release of a statement saying he had "died peacefully" that morning at Windsor Castle. The Duke's daughter-in-law, Sophie, Countess of Wessex and Forfar, described his death as "...so gentle. It was just like somebody took him by the hand and off he went." The Queen was at her husband's bedside when he died. The death certificate, certified by Sir Huw Thomas, head of the Royal Medical Household, stated the cause of death as "old age".
Operation Forth Bridge.
The national plan for publicly handling the Duke's death was called Operation Forth Bridge, named after the Forth Bridge near Edinburgh, the city of his dukedom. According to the College of Arms, the original plan was amended in light of the COVID-19 pandemic.
Initiated upon his death, the plan included a press release issued by Buckingham Palace simultaneously to the BBC, the national broadcaster of the United Kingdom, and PA Media; protocol assumes the Lord Chamberlain consulted with the Queen prior to the press release. The plan included duties to disseminate the news across the Commonwealth of Nations. In Australia, one of the Commonwealth realms of which Elizabeth was queen, the responsibility to inform the government and public was that of Governor-General David Hurley.
At the time of the release, flags were lowered to half-mast, where they remained for a period of national mourning lasting until 8 am on the day following the Duke's funeral. All Union Flags and national flags were lowered, and government guidance suggested that other flags on governmental buildings – for example, flags of the Armed Forces or Pride flags – be replaced with a Union Flag at half-mast for the mourning period. However, the Royal Standard continued to be flown at full-mast at Windsor Castle, as it represents the presence of the living monarch. 
Members of Parliament (MPs) wore black ties when in the House of Commons, and also wore black armbands on their left arm, traditional symbols of mourning. No laws were passed during the eight-day mourning period.
At 6 pm on 9 April, the tenor bell of Westminster Abbey began ringing, and was tolled once every minute for 99 minutes, to reflect the Duke's lifespan, the custom known as the death knell. 
The majority of military rehearsals for the funeral procession took place at Pirbright Camp and a full dress rehearsal took place at Windsor Castle on 15 April.
Funeral.
The Duke's funeral took place on 17 April 2021 in St. George's Chapel at Windsor Castle.
Procession and service.
The Duke was given a royal ceremonial funeral, not a state funeral, which is usually reserved for monarchs. He had indicated a wish for minimal "fuss"; as such, he did not lie in state, though he did "lie at rest" in the private chapel at Windsor Castle. Prior to the service, the coffin was moved from this chapel to the Inner Hall of the castle, where prayers were said. The Duke's wishes were said to be for a military funeral conducted at St George's Chapel and burial in King George VI Memorial Chapel alongside King George VI, Queen Elizabeth The Queen Mother, Princess Margaret and his wife, Queen Elizabeth II after her death. This royal ceremonial funeral is the same level of honour as those given to his former daughter in law Diana, Princess of Wales in 1997 and to his mother in law Queen Elizabeth The Queen Mother in 2002. The funeral of Prince Philip was televised.
Before the service, bands from the armed services were marched onto the Quadrangle of Windsor Castle. They performed music including "Jerusalem", "I Vow to Thee, My Country", "Supreme Sacrifice", "Isle of Beauty" and "Nimrod".
Plans for the funeral, which occurred on 17 April, a Saturday, included the Duke's coffin being carried by the Grenadier Guards to the State Entrance of Windsor Castle before being taken to the West Steps of St George's Chapel at 2:45 pm on a custom-built Land Rover Defender hearse in Edinburgh green that the Duke helped design. The Quadrangle, the point from which the coffin departed, was lined by the Household Cavalry, the Foot Guards, as well as military detachments from units with special links to the Duke. Defence advisors from Australia, Canada, New Zealand, and Trinidad and Tobago were also present, representing the Duke's links to units in their respective countries. The coffin was draped with his personal standard, carried his naval cap and his sword, and had a wreath of white roses and lilies placed on it with a note written by the Queen. The band of the Grenadier Guards led the procession from the Quadrangle to Horseshoe Cloister, followed by military commanders and chiefs of staff.
The Duke's four children, three of his grandchildren, Prince William, Duke of Cambridge; Prince Harry, Duke of Sussex; and Peter Phillips, his nephew by marriage David Armstrong-Jones, 2nd Earl of Snowdon, and his son-in-law Timothy Laurence, as well as the Duke's household staff (including Brigadier Archie Miller-Bakewell), walked behind the coffin. They were followed by the Queen, who was travelling in the Bentley State Limousine, accompanied by Lady Susan Hussey, her lady-in-waiting. Personnel from the Royal Navy, the Royal Marines, The Highlanders, 4th Battalion, Royal Regiment of Scotland and the Royal Air Force lined the procession route. The King's Troop, Royal Horse Artillery fired minute guns throughout the procession. The Duke's favourite driving carriage, accompanied by some of his grooms and pulled by his two black Fell ponies, Balmoral Nevis and Notlaw Storm, stood in the Quadrangle as the procession passed by. On the driver's seat of the carriage were laid the Duke's cap, whip and driving gloves.
At the West Steps of the chapel, which were lined by the Household Cavalry, eight pallbearers from the Royal Marines carried the coffin. A guard of honour was formed from members of The Rifles, while the Band and Bugles of The Rifles played the national anthem and the Royal Navy pipers piped the side at 2:53 pm, followed by a national minute's silence at 3 pm. Around 730 members of the Armed Forces were present at Windsor Castle, including four military bands.
David Conner, Dean of Windsor, and Justin Welby, Archbishop of Canterbury, officiated at the funeral service. The Duke's insignia was displayed on cushions on the altar in St George's Chapel, including honours and decorations bestowed by the United Kingdom, Canada, Australia, New Zealand, and Papua New Guinea, as well as other member-states of the Commonwealth; his field marshal's baton and Royal Air Force wings; and insignia of the Danish Order of the Elephant and Greek Order of the Redeemer. During the service, there was a reduced choir of four singers conducted by chapel director of music James Vivian; the organist was Luke Bond. The four singers were soprano Miriam Allan and three lay clerks (Tom Liliburn, Nick Madden and Simon Whiteley).
No sermons or eulogies were delivered at the service at the Duke's wish. The ceremony highlighted his links to the Royal Navy and his passion for the sea. The Royal Family confirmed that for the memorial, the Duke had handpicked all the music himself. His choices were "imbued with his long, proud legacy with the Royal Navy, and a deep love of Britain's musical heritage."
The funeral started with the choir singing the "Funeral Sentences", composed by William Croft. The first lesson, from Ecclesiasticus, chapter 43, verses 11–26, was read by the Dean of Windsor. The second lesson, from the Gospel of John, chapter 11, verses 21–27, was read by the Archbishop of Canterbury. Psalm 104 was sung to a setting by William Lovelady that the Duke had commissioned. During the service, Britten's setting of Psalm 100 was sung by the choir at the request of the Duke of Edinburgh himself. The music included the hymn "Eternal Father, Strong to Save", which is traditionally associated with seafarers, Benjamin Britten's "Jubilate in C" (also commissioned by the Duke), and the Russian Kontakion of the Departed to an arrangement by Sir Walter Parratt. The music performance entailed meticulous planning of keys, built around G minor and G major; other connecting royal, historical and local themes were also included in the music for the service. The Dean of Windsor paid tribute to the Duke's "unwavering loyalty" to the Queen and "his service to the nation and the Commonwealth" in the bidding. The Dean gave the commendation as the coffin was lowered into the Royal Vault, while the pipe major of the 4th Battalion of the Royal Regiment of Scotland played the lament "The Flooers o the Forest" while walking from the North Quire Aisle to the Dean's Cloister. The service finished with the proclamation of the Duke's styles and titles by Thomas Woodcock, Garter Principal King of Arms, and the bugle calls "Last Post" (sounded by the Buglers of the Royal Marines), "Reveille" (sounded by the State Trumpeters of the Household Cavalry) and "Action Stations" (sounded by the Buglers of the Royal Marines). The Archbishop of Canterbury pronounced the blessing, which was followed by "God Save the Queen". After the service, organist Luke Bond played Johann Sebastian Bach's Prelude and Fugue in C minor, BWV 546.
The Duke's remains were temporarily in the Royal Vault at St George's Chapel. Following the Queen's death, his remains were moved to the King George VI Memorial Chapel inside St George's, where the couple were buried next to each other.
Attendees.
Regulations against mass gatherings brought in because of the COVID-19 pandemic meant that the number of guests attending the funeral was limited to thirty. This limit did not include anyone working at the funeral, such as pallbearers and clergy. As a result, only members of the Royal Family and a limited number of relatives attended the ceremony inside the chapel. The Queen sat alone at the service. Per COVID-19 regulations, households were separated by two metres. All attendees were required to wear masks and not sing.
The funeral departed from royal protocol with all family members attending in formal day dress rather than military uniforms, something which also occurred at the funerals of Diana, Princess of Wales, and Princess Margaret, Countess of Snowdon, though protocol was followed for the funeral of the Queen Mother.
Prince Harry, who was then living in the United States, had planned to return to the UK for the Duke's 100th birthday in June and the unveiling of a statue of his mother in July. He instead returned six days prior to