The Enelsian Invasion

The Enelsian Invasion was an attempted takeover of Earth by the alien Enelsians, that came to light on August 4, 1997 in Astro City and culminated with a worldwide battle the next day, between heroes of the world and the the aliens.

Precursors

In 1995, the Honor Guard's alien detector was malfunctioning after The Zonn had attacked sometime prior. This enabled the Enelsians to slip their agents and spies in undetected by heroes and the unsuspecting public both.
The spies took stock of the super powered being and heroes and the ways of Earth. The most notable agent, Mr. Bridwell felt somewhat sympathetic towards the Human race and whether or not to transmit his report. He used the hero Crackerjack as a microcosm of humanity for his final test. Crackerjack reminded him a lot of the Enelsians themselves. Mr. Bridwell only sent his report after being irritated by a bunch of gossiping old ladies, when the females of the Enelsians are the warriors of the race.

Hero Distrust

The next phase of their invasion plans, as more agents snuck onto the planet, was to try and discredit and ruin reputations of heroes. Outspoken heroes like Winged Victory or ones more on the downside of public opinion, made easy targets to get public sentiment against them.
Mr Bridwell, even took to impersonating Crackerjack in a series of armed robberies in June 1997 before finally being found out by Altar Boy.