Why did the Senate grant Octavian extraordinary provincial commands in 27 BCE?
The Senate acted under direct military threat from Antony's surviving legions
The Senate was legally bound to do so under the terms of the Lex Titia of 43 BCE
The Senate granted the powers after Octavian ostensibly restored the Republic and offered to relinquish his extraordinary authority, and in response entrusted him with the frontier provinces✓Bonne réponse
The Senate acted mainly to prevent Lepidus from returning to public life
Explication
The traditional account holds that Octavian's gesture of returning power to the Senate in 27 BCE was answered by the Senate voting him continued command of the provinces that needed a strong military hand, formalizing his authority under a republican veneer. Antony's legions no longer existed as an independent threat by then, the Lex Titia had governed the earlier triumvirate rather than this later settlement, and Lepidus, long since politically sidelined, was not the Senate's concern in 27 BCE.