Trade goods from across the galaxy pass through Corellia every day, and Coronet Shipping has always been the busiest trade hub on the planet. Before the war, all manner of freighters visited its landing pads, bearing goods both legal and otherwise. Millions of credits worth of commerce occurred there every day.
When the Republic established its beachhead at the Blastfield Shipyards, the Empire was quick to secure Coronet Shipping for itself as a rapid-response staging area. The main ground approach to these landing pads was destroyed by Imperial forces, rendering the area inaccessible to infantry and walker units. Aerial patrols keep Republic assault shuttles at bay and protect the Empire's elite troops.