Hardcastle was a General of the United States Army assigned to destroy an asteroid that was heading towards Earth. When Superman arrives to help, Hardcastle grew furious at thought of having an alien with no allegiance help him. An alien known as Prometheon was found to be active on the asteroid and the general was still determined to destroy the asteroid. He activated the charges on the asteroid even though Superman was still on it.
Hardcastle led an attack against the creature and ordered his men to fire missiles at it. Superman came to Hardcastle and told him to stop firing missiles at the creature because it absorbs heat. Hardcastle refuses to believe him, saying that he believed him before and failed. He eventually believed Superman when his missiles failed to harm Prometheon and he orders his men to stop firing missiles.
Hardcastle still distrusted Superman after the encounter with Prometheon. General Hardcastle secretly formed an alliance with Lex Luthor to create Project Achilles, a military project designated to find the weaknesses of Superman and Supergirl. Hardcastle led his military against the Parademons when Darkseid brainwashed Superman into becoming his pawn.
The general captures both Superman and Supergirl with a Kryptonite missile that was made by Lex Luthor, Hardcastle took in Superman for questioning and believes that Superman always was plotting to conquer Earth. After the Man of Steel tried to escape, Hardcastle tries to inject Superman and Supergirl with liquid kryptonite that would effectively kill them. The two superheroes escaped with Lois Lane's help.
Years after Project Achilles, Hardcastle lost his title and was forced into early retirement. However years later Supergirl, Question, and Green Arrow actively sought out Hardcastle after a series of Z-8 robots attacked the trio when they were looking into Supergirl's bizarre assortment of nightmares. Reluctantly, Hardcastle told them what he knew. For years, long before the Justice League was first formed, an organization was formed to keep an eye out for the heroes, should they turn rouge. Among their work included Volcana and the original Royal Flush Gang. After their interrogation, Galatea later arrived at Hardcastle's home and killed him, as a means of tying up loose ends.
General Hardcastle and Professor Hamilton have an argument.
Hardcastle forms an alliance with Lex Luthor.
Hardcastle threatening Superman while questioning him.
Hardcastle in early retirement after his defeat by Superman a few years ago.
Hardcastle being questioned by Supergirl and Green Arrow.