The Duke of Edinburgh's final public engagement before he retires at the age of 96 will take place on August 2, Buckingham Palace has said.
Philip will attend a Royal Marines' charity parade outside the Queen's London residence before he steps back from his official duties.
Earlier this year it was announced he would retire after the summer.
A Buckingham Palace spokeswoman said that the parade would "bring His Royal Highness's individual programme to a conclusion, although he may choose to attend certain events, alongside the Queen, from time to time".
The parade will mark the end of the 1664 Global Challenge, which raises money for The Royal Marines Charity.
This year it has seen marines from around the country running 16.64 miles each day for 100 days, totalling a distance of 1,664 miles.
The number is symbolic for the naval fighting force, which traces its roots back to the year 1664.
Philip became its Captain General in 1953, replacing King George VI after his death.
It was announced in May that the Duke, who turned 96 in June, would step down, but the palace said it was not for health-related reasons.