Following his triumph over Pompey, Caesar had no serious power rivals who could challenge his supremacy and he was given official dictatorial authority by the Senate. Why is it then that Augustus is almost universally considered to be the first emperor and not Caesar? Is it because he was assassinated? Is it because Augustus did not inherit his powers directly and had to fight a civil war? Is it because Augustus gained additional powers?
Hi, this is a rather common question, and of course there is always the option for more discussion, but I'd suggest you have a look at this answer by /u/Polybios.