Why did the Roman Senate order Julius Caesar to give up his army?

The Roman Senate’s demand that Julius Caesar relinquish command of his legions was rooted in a complex political struggle regarding his legal immunity and future career.12

As Caesar’s term as governor of Gaul neared its end, he sought to stand for the consulship to ensure his political survival. If he were to step down from his provincial command before entering office, he would become a private citizen, leaving him vulnerable to prosecution by his political enemies. To prevent this, Caesar insisted on maintaining his military command until he could secure the consulship.2

Conversely, the Senate, influenced by Caesar's rivals and Pompey the Great, sought to force his return to Rome as a private citizen, effectively ending his political career. By 50 BCE, the Senate passed resolutions demanding he lay down his command. Caesar viewed these orders as a direct threat to his safety and status. When the Senate declared him a public enemy in January 49 BCE for refusing to comply, Caesar chose to cross the Rubicon with his army, initiating the Roman civil war.321