In addition to ruling among devas above Earth, he ruled on Earth as well, having acquired splendid glory. The danavas (demonized Asuras in space), sworn enemies of the devas from time immemorial, neither liked Sakka nor his expanding influence.
When Buddhism spread to ancient Greece (Bactria and the Indo-Greco empire) there was a "Sakka-stan" in the vicinity of modern Afghanistan. Indo means Indian but is also a title for Sakka who is also known as Indra. Indo-Greeks can equally well refer to both Indian and honoring Sakka, a protective ET.
So one day in fleets of spacecraft (vimana) they invaded Sakka's empire with a large army to usurp power. Boarding his golden chariot of the gods (devas) drawn by a thousand horsepower engine, Sakka put up a formidable resistance with his army of "shining ones." But the devas were losing the battle and began to retreat.
Bas relief depicting Sakka and female companions descending to Earth to intervene (ignca.nic.in).
Sakka's flight captain (charioteer) Matali noticed the retreat of the deva army (hosts) from the theater of operations. So he turned the spacecraft and flew quickly through the sky (akasha). Flying high, Sakka noticed the avian-hybrids (Garudas) among the trees likely to be hit by his soaring craft. But with the enemy in hot pursuit, any change in direction would mean his capture by the demons.
Nevertheless the compassionate commander of the space devas, in order to spare the Garudas in his flightpath, ordered Matali to turn the ship around and face the demons. Sakka sounded an alarm, a mighty battle cry, and manned his weapon station to strike at the tailing enemy.
When the demons saw Sakka, ruler of the devas, turning around preparing to resume the fight, they fled. They assumed he must have renewed his forces with fresh reinforcements or, true to his chivalrous reputation, had resorted to some fresh battle strategy. And soon the devas regained their realm having spared the young Garudas.