He was Commander of the Italian XV Corps from 1939 to 1940 and became head of the CTV at General Franco's request.

However Italy's commitment in Spain had drained it of resources which made it not ready to fight against Britain and France.

In the summer of 1940, Berti replaced Francesco Guidi as the commander of the Italian Tenth Army in Libya.

Halted at Sidi Barrani by logistical problems, Berti deployed his advanced units in a series of fortified strongpoints.

However, prior to this, General Berti went on sick leave and Italo Gariboldi took his place temporarily.

On 9 December 1940, Berti was on leave when British General Richard O'Connor launched Operation Compass.