Prince William complimented British soldiers practicing for King Charles’ impending birthday parade, saying, “Difficult conditions but you all did a really good job.”

After passing out during a practice for the forthcoming King Charles birthday parade, a British soldier carried on playing the trombone.

One of the band members reportedly passed out while practicing on Saturday in the sweltering heat of London, according to BBC News.

He briefly lost consciousness, though, and rose back up to pick up his guitar before being led away for medical attention.

On Saturday morning, Prince William posted a tweet about the event on the Prince and Princess of Wales’ Twitter account.

Thank you so much to all of the soldiers who participated in the Colonel’s Review this morning despite the heat. Despite the challenging circumstances, you all performed an excellent job. I’m grateful. W,” the 40-year-old Prince of Wales wrote.

Although Queen Elizabeth staged the yearly celebration at the same time each year, the celebrations will mark the first birthday procession of King Charles’ reign.

The Welsh, Irish, Scottish, Grenadier, and Coldstream Guards Household Division’s more than 1,500 soldiers and 300 horses marched for Prince William to examine during the practice.

Additionally, some brand-new songs written especially for the occasion by members of the Band of the Welsh Guards were played.

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The royal family, including Kate Middleton and Queen Camilla, as well as millions of television watchers, will watch the music and the parade next Saturday.

The procession will mark a year of firsts for both William and the King, who will be participating in his first parade as Prince of Wales.

The rehearsal position was also filled by William for the first time on Saturday since he was appointed ceremonial Colonel of the Welsh Guards soon after the passing of Queen Elizabeth in September.

When he was Colonel of the Irish Guards last year—a position that is currently held by his wife—he undertook the Colonel’s review.