The Tercio de San Severo was established in Napels by nobleman, fourth Prince of Sansevero and Maestre de campo Paulo di Sangro (1605-1636) at the beginning of the year 1634. With its 3.500 men divided into 24 companies it had the size of a coronelía.
In May 1634 the T. de San Severo was transported to Savona and detached to the expeditionary army of Cardinal Infant Fernando. During its march to southern Germany it lost almost half its strength (it was down to 1900 men) and it hadn’t even been battle-tested yet. Apart from that it seems that Paolo di Sangro was not a very able commander.
In September the T. de San Severo took part in the battle of Nördlingen, in a reserve position behind the Albuch. After the battle it was dissolved and its component parts were spread over other Neapolitan tercios.