What two groups were key to Julius Caesar's popularity?

The First Triumvirate and the military.

Explanation:

Julius Caesar was was a very powerful and renowned Roman general and statesman who transformed the Roman empire into a very powerful and formidable republic by expanding its geographical reach and establishing its imperial system. Caesar's popularity was enhanced as a result of his military exploits during his service at the Roman army, as well as his subsequent alliance with Gnaeus Pompey Magnus (the powerful military general and political leader) and Marcus Licinius Crassus (a renowned army general, often referred to as the richest man in Rome at that time). The alliance is popularly known as the First Triumvirate. This alliance coupled with Caesar's military exploits and victories contributed to opening doors of opportunities for him. He grew to become the governor of the Roman Province in Spain. He also served as the Governor of Gaul, and ultimately became the "divine" Roman leader with the title of "Dictator for Life".

More so, Caesar was an excellent negotiator who was able to negotiate with the pirates who kidnapped him, and subsequently gained his freedom, after which he went after the pirates with the naval force; captured them, and executed them. He also deployed his negotiation tactics in reconciling Pompey and Crassus.

Caesar is remembered till date for the uncommon transformation that he brought to the Roman empire.

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