Thanagar began in ancient times as a hard world with a primitive and savage culture. Its inhabitants possessed extensive knowledge of agriculture, mathematics, and philosophy, achieving many developments in technological advancement. Among these was the utilization of Nth metal, a strong metal known for it's ability to negate gravity, making it perfect for the flying Thanagarians.
The Thanagarians once worshiped a pantheon of extradimensional entities known as The Great Old Ones. As they matured the Thanagarians stopped worshiping them and 21st Century Thanagarians bowed down to no higher power. As Hawkgirl proclaimed, her race was a warlike people, and sometime after the utilization of Nth metal, the Thanagarians began a conquest of neighboring planets and star systems. They established a state of intergalactic hegemony known as the Thanagarian Empire.
The Thanagarian-Gordanian War
With the expansion of its military forces throughout its many years of conquest, the inhabitants of Thanagar eventually came into contact with the Gordanians, a cruel race of intergalactic slavers. Skirmishes over territory between the two worlds eventually escalated into an all-out war, known as the Thanagarian-Gordanian War. The Thanagarian Empire, with its various technological advancements, alongside the riches it had gained through its years of planetary conquest, saw constant victory in the early stages of the war. The conflict soon proved to be a long and bloody one, however, as the war saw heavy casualties on both sides; additionally, the conflict saw the Thanagarians placing much of their wealth into military spending and development of weaponry in support of the war effort, depleting it of its many riches and other resources. A primary objective shared betwen the two superpowers would be to lead a direct assault against the opposing side’s homeworld, resulting in a quick and decisive victory.
While Thanagar itself remained virtually defenseless, the Gordianian homeworld was surrounded by an impenetrable defensive line, which effectively blocked it from any sort of frontal attack. It was for this reason, that the Hyperspace Bypass Generators were developed. In the later years of the conflict, however, the situation had grown considerably worse for Thanagar, as with the Gordanians closing in on the planet, it appeared that they would emerge victorious. As the war had depleted Thanagar’s forces of a great many of its natural resources, they were unable to build a bypass in close proximity to their target. Earth, however, was a planet seemingly abundant in resources, making it a primary target. Not wishing to arouse suspicion towards themselves with a sudden arrival, however, the Thanagarians then sent an agent, Lieutenant Shayera Hol, to Earth in order to ensure an "alliance" between the two worlds.
Invasion and Occupation
The alliance was established with Earth shortly after the "Gordanians" began an apparent attempt to invade the planet. The Thanagarians then arrived, offering to construct a planetary force field to aid Earth's inhabitants in fending off the impending threat; however, the Gordanian invasion of Earth was revealed to be a false flag operation engineered by the Thanagarians and the planetary force field was in reality a Hyperspace Bypass Generator, which the Thanagarians would use to lead a direct assault on the Gordanian homeworld and end the war, though at the cost of Earth's destruction; a fact that Thanagarian general Hro Talak — head of the invasion force and Shayera's fiancé — stated was a necessary sacrifice for the sake of Thanagar. The Thanagarians then began their invasion of Earth, taking control of the Justice League's Watchtower, and as Earth's protectors were forced into hiding, began construction on the generator. The subsequent occupation of Earth was one of exceptional brutality, as those who attempted to fight back faced imprisonment and torture. Because of this, Shayera Hol betrayed her people, with the Justice League soon launching its counterattack, resulting in the destruction of the Thanagarian fleet sent to support the occupation. The final blow, however, was delivered in the form of Batman manually guiding the Watchtower to crash into the generator, as with its destruction, the Thanagarians were forced to leave Earth.
Following the destruction of the hyper-space bypass generator, along with a significant portion of their fleet, Hro and the remainder of the invasion force returned to Thanagar, only to find it under assault from the full force of the Gordanian fleet. In a desperate move, Hro Talak led a suicide attack, ramming his command ship into the Gordanian flagship, the subsequent explosion resulting in the destruction of a majority of the Gordanian fleet. However, the general's sacrifice proved to be in vain, as the rest of the Gordanian fleet then closed in on Thanagar, securing its victory.