Iroh was seen with two Imperial Firebenders at his side while writing a letter during the Siege of Ba Sing Se.  While out to capture her brother and uncle, Azula was accompanied by at least thirty of these soldiers in her ship. Iroh and Zuko were able to defeat these soldiers easily, after discovering that they were about to be taken as prisoners. After being advised by Lo and Li, Azula decided to leave the Royal Procession in favor of a smaller, elite team, and set off to enlist Mai and Ty Lee.
During the Day of Black Sun they were seen in Fire Lord Ozai's secret bunker to serve as protection during the eclipse in the event that an enemy managed to breach the underground facility. As they were deprived of their bending, they were carrying spears.
The Royal Procession was briefly seen at the coronation of Phoenix King Ozai. Imperial Firebenders held up the banners of the Phoenix King.
Before her coronation as Fire Lord, Azula slipped into a case of severe paranoia and ended up banishing nearly all her staff, including the Imperial Firebenders present at the palace, as mentioned by Lo and Li. Imperial Firebenders were seen as part of the crew of the airship fleet, burning a large section of the Wulong Forest and defending the ships from intruders. After Fire Lord Zuko ended the War, it is probable that these troops have been reinstated as bodyguards.
The members of the Royal Procession wore helmets that had a three point theme. There were three red spikes on the top of the helmet, three eye holes and shard-shaped mouth holes. Captains were distinguished by the fact that their helmets had the same general design, but lack face masks. During the time when Ozai declared himself the Phoenix King the uniforms of the members of the Royal Procession were a black inverted version of the original, i.e. whatever was black was red and vice versa.