defeat. Publius Scipio was tasked with holding Hannibal in Spain and Gaul, which was the essential prerequisite for implementation of the next step: invasion of Africa; Spain was a secondary objective. The Gallic rebellion in Cisalpine Gaul delayed Scipio's arrival to Spain, and probably saved his army from destruction, as Hannibal had mobilized 87,000 – 102,000 soldiers and had moved slowly through Spain to meet and beat the Romans before marching for Italy, whereas Scipio had 24,600 soldiers. The speed of Hannibal's march across Gaul scuttled the Roman plan: Hannibal had already crossed the Ebro before Scipio had even set sail, so that by the time the Romans arrived at the Rhône, Hannibal had already crossed the river, which Scipio discovered only by chance. Scipio now had no way to succeed in his primary objective of holding Hannibal out of Italy, but he could still go to Spain, the secondary objective. Scipio's decision to send his brother to attack Spain mirrors the strategy Memnon of Rhodes advocated against Alexander the Great. Memnon advocated launching an attack against Macedonia in conjunction with Sparta and Athens, with the help of the superior Persian fleet, while Alexander was busy in Asia Minor. Due to the eventual success of the Scipio brothers in Spain, Hannibal looked for but never received reinforcements from Spain during the war, and one historian has speculated that if Publius Scipio had not sent his army to Spain in 218 BC, his son probably would not have won at Zama in 202 BC. On the other hand, Scipio missed the chance to concentrate 40,000 infantry and 4,000 cavalry against Hannibal in the Po valley by not taking his army to Italy and probably missed the chance to attack Hannibal as the Carthaginians emerged from the passes, exhausted and diminished in numbers as Scipio had originally planned. Had Scipio brought his army back to Italy, Rome would have had the option to launch the invasion of Africa by allowing Sempronius to set sail from Sicily, or order him to join Scipio, so Hannibal would have faced 60,000 Roman soldiers instead of 40,000 at the Battle of Trebbia, from this angle Scipio made a grave mistake by sending his army to Spain. Notes References Sources and references Further reading Cissa Battles involving the Roman Republic Battles in Catalonia Cissa Cissa