[1] At the time of his birth, Portugal was part of the Iberian Union with Spain; his father was a member of the Council of Castile who was made Count of Sentar in 1636, while Pedro himself received the title Marqués de Assentar.

[2] He became military commander of Novara in 1662, an important commercial centre in the Spanish-ruled Duchy of Milan, before being appointed Governor of Ceuta three years later.

In 1673, Spain became involved in the Franco-Dutch War as an ally of the Dutch Republic and Assentar transferred to the Spanish Netherlands as commander of the Army of Flanders.

[1] On 11 August 1674, his unit formed part of an Allied army led by William of Orange which sought to outflank French forces under Condé near Seneffe.

[3] They were finally forced to retreat in the early evening, leaving behind their dead; these included Assentar, whose body was later returned by Condé for burial.