The invasion was preceded by an air strike on the Presidential Palace in Baghdad on 19 March 2003. The following day coalition forces launched an incursion into Basra Province from their massing point close to the Iraqi-Kuwaiti border. While the special forces launched an amphibious assault from the Persian Gulf to secure Basra and the surrounding petroleum fields, the main invasion army moved into southern Iraq, occupying the region and engaging in the Battle of Nasiriyah on 23 March. Massive air strikes across the country and against Iraqi command and control threw the defending army into chaos and prevented an effective resistance. On 26 March the 173rd Airborne Brigade was airdropped near the northern city of Kirkuk where they joined forces with Kurdish rebels and fought several actions against the Iraqi army to secure the northern part of the country.