Later, in 1912, he was in Libya where, as soon as he arrived, he directed the Battle of Sidi Garabaa, also in an Italian defeat.

Mambretti was a commander general during the First World War, his name is remembered for the Battle of Mount Ortigara, which led to the death of thousands of soldiers and his removal from command, since among other things he had also achieved many defeats in previous clashes.

A particular fact, also testified by letters from Angelo Gatti and Luigi Cadorna, was the prejudice that Mambretti was a bringer of bad luck.

The Austrians, after a great preparation of artillery, attacked and took the Ortigara from us, despite a strenuous defense.

The defeat suffered on Ortigara and above all the great loss of men despite the abundance of means forced General Cadorna to remove Mambretti from his post.