Six days (March 13, 1815) before Napoleon reached Paris, the authority of the Congress of Vienna had declared him an outlaw. Four days after the declaration, the mobilized armies of Prussia, Austria, Russia, and the United Kingdom planned an attack to defeat Napoleon. Napoleon was aware that once he attempted to attack one or more of the allies of the Seventh Coalition in the French invasion, his only chance of retaining his power would be to attack first before the mobilization of all the armies of the Coalition. His goal was to destroy the existing forces of the Coalition that were in the south of Brussels before they were commanded. Once this happened, Napoleon might be able to drive the British army back to the sea and defeat the Prussian army in battle.