Complex sentence: The young "alferes" was an apt choice for the task; he was well connected in the imperial capital (his uncle, married to a paternal aunt, was Minister of War), cultured, and well educated.
Split into simpler sentences: The young "alferes" was an apt choice to carry out the task. He possessed good connections in the imperial capital (his uncle, married to a paternal aunt, was minister of war), and he was also cultured and well educated.