|~ Emperor Palpatine to his Royal Guards|
The Imperial Guard was actually formed sometime prior to the rise of the Galactic Empire during the days of the Galactic Republic. Formed during its final years, the Imperial Guard was simply known as the Red Guard and were founded by Sheev Palpatine for the sole purpose of acting as his personal bodyguards. The guard was created after Palpatine was elected Supreme Chancellor of the Galactic Republic and they were personally chosen and recruited from the Senate Guard and eventually replaced their blue armored counter-parts towards the end of the Clone Wars. The red robes of the guard melted in perfectly with the color scheme of the Chancellor's office and were always stationed at the entrance even prior to the outbreak of the Clone Wars. Despite the presence of the guard however, Palpatine kept them a secret and instead had Senate Commandos protect him until the final stages of the Clone Wars when he had the guards show up in public where they remained there silent and imposing figures.
Era of the Empire
At the end of the Clone Wars, Palpatine declared himself as the new Galactic Emperor and dissolved both the Republic and the Confederacy of Independent Systems and formed the two warring governments into the Galactic Empire. After the formation of the empire, the Imperial Guard was the new official name and took their positions at Palpatine's side where they were occasionally relieved by the Coruscant Guard which would step in sometimes as Palpatine's protectors. By the time of the empire, the Senate Guard was dissolved completely and was phased out in favor of the Imperial Guard and Stormtroopers. In 14 BBY, several guardsmen accompanied Darth Vader and Sidious on a mission to Ryloth in an attempt to lure out the opposing Free Ryloth Movement from hiding. The shuttle carrying them crashed however and several guards were killed in the process. Two of the guards however, managed to survive the crash and accompanied their Sith masters, but were later ambushed by rebel forces on the planet. The mission however, would end in a success for the empire and almost all Ryloth rebel forces were wiped out completely.
Throughout the Galactic Civil War, the Imperial Guard served as elite shock troops and personal enforcers for the emperor as they often served in various roles from protectors to assassins and other roles. they dawned their iconic blood-red colored robes and wore advanced combat armor and helmets to conceal their identities and carried various weapons such as force pikes, vibroblades, and other concealed weapons. While the primary function of the Imperial Guard was for the safeguard and protection of the emperor, Palpatine did not make exclusive use of them and had them sent on other tasks such as two of the guarding Lord Vader in his castle on Mustafar. In 0 BBY, Vanee warned Vader of the arrival of Director Orson Krennic to discuss the plans and future of the ambitious Imperial project, the Death Star.
While the guards were some of the best soldiers the empire had to offer, the Battle of Endor would end up becoming the ultimate failure of the order and it wasn't on their part. After Luke Skywalker turned himself into the Imperial authorities, Palpatine confronted Skywalker after Vader brought him into his thrown room on the Death Star II and has his guards exit while he personally met with Vader and his son, Luke. A fight between the Sith father and the Jedi son erupted and in the end, Palpatine was betrayed and killed by Vader and the second Death Star would later be destroyed at the hands of the Rebel Alliance killing many Imperial personnel and guards onboard in the process.
New Republic Era
Following the aftermath of the Battle of Endor and the rise of the New Republic, the Imperial Guard remained active despite the death of the emperor and were escorting Imperial General Jylia Shale for peace talks between the fragmenting Galactic Empire and the rising power of the New Republic on the planet of Chandrila. An attack broke out on the planet during the peace talks and the present royal guards ended up fighting and took down five New Republic Senate Guards and began guarding the Imperial entourage. In the aftermath of the failed negotiations, the brother of Arilz Hadrassian had joined the Imperial Guard during the Battle of Jakku. His helmet was later claimed by his brother, who was a member of a proxy group for the First Order and he sold his helmet to Ransolm Casterfo, a Centrist senator of the New Republic.