 In January 49 B.C., Caesar led his legions across the Rubicon River from Cisalpine Gaul to Italy, thus declaring war against Pompey and his forces.In August 48 B.C., with Pompey in pursuit, Caesar paused near Pharsalus, setting up camp at a strategic location.When Pompey's senatorial forces fell upon Caesar's smaller army, they were entirely routed, and Pompey fled to Egypt.