Later he fought against Braccio da Montone for her, taking part in the conflict in the Abruzzi of 1424: after Muzio's drowning, he commanded the vanguard at the Battle of L'Aquila.

Later he was at the service of Pope Martin V and of the Republic of Florence, being decisive at the Battle of San Romano against the Sienese.

In 1434, after the treaty between Pope Eugene IV and Joanna (1434), Attendolo was made Gran Connestabile (commander-in-chief) of the Kingdom of Naples.

Subsequently, he fought mostly alongside Francesco Sforza and was victorious against Niccolò Piccinino at the Battle of Anghiari (1440).

He clashed with Sforza, who now led the army of the Repubblica Ambrosiana of Milan, at the battle of Caravaggio (15 September 1448), being severely defeated.