Your general has landed on the airfield. You need to bring him into the fields across the river to inspect (and activate) your armies. From that point you need to build your defenses for a coming enemy attack, which can be quite hard in case you're not prepared.

The attack will start from the moment you have brought back your general to the airport, therefor you can choose for yourself how long you need to prepare. After the attack, you'll need to mob up the remaining enemy units, which shouldn't be that hard at all.