President Joe Biden marked Tuesday’s eighth anniversary of one of the saddest days of his life, the death of his son Beau, by attending a memorial Mass and visiting his gravesite. Mr Biden, his wife, Jill, and other family members prayed for Beau Biden during the Mass at St Joseph on the Brandywine, the Roman Catholic church where the president worships during weekends at his home near Wilmington, Delaware. Afterward, the family visited Beau Biden’s gravesite in the church cemetery. The first lady carried a bouquet of flowers. Beau Biden was 46 when he died of brain cancer in 2015. His father was vice president. The eldest of Mr Biden's three children, Beau Biden served two terms as Delaware attorney general before declaring a run for governor. Many saw in him the same aspirations that brought his father to the White House. In fact, Joe Biden often says his son is the one who should have been president — not him. Beau Biden also served in Delaware’s Army National Guard, including a deployment to Iraq, where the president says he was exposed to toxic gases from pits where the military burned waste. Mr Biden has linked his son's cancer to his exposure to burn pits. Beau Biden is the son of Joe Biden and his late first wife, Neilia, who was killed in a 1972 car crash that gravely injured Beau and younger brother Hunter, and also killed their baby sister. Beau Biden’s daughter, Natalie, graduated from high school on Sunday, with her grandparents in the audience. She will attend her father’s alma mater, the University of Pennsylvania, in the fall. While Tuesday's remembrance of Beau Biden was private, the president publicly mourned his son on Monday during a Memorial Day address at Arlington National Cemetery in Washington. For Mr Biden, his son's death and the annual holiday honoring Americans who paid the ultimate sacrifice serving the United States in uniform are inextricably linked. He told the audience that Tuesday “marks eight years since we lost our son, Beau." “As it is for so many of you, the pain of his loss is with us every day, but particularly sharp on Memorial Day. It’s still clear,” Mr Biden said. “Tomorrow is his anniversary. But so is the pride Jill and I feel in his service, as if I can still hear him saying, ‘Dad -- it’s my duty, Dad. It’s my duty.’ Duty.” Read More Biden invokes late son Beau’s memory as he pays tribute to fallen US soldiers Beau Biden: The story of Joe Biden’s late son Critics say Biden is lying about how his son Beau died in Iraq – they are ignoring the full story Biden will welcome Sunak to White House next week AP News Digest 9:30 a.m. Sunak to visit Washington DC for talks with Joe Biden