Complex sentence: King Martin sent his son Martin the Younger to reconquer Sardinia, and just before his own death he won the battle of Sanluri (San Luis, San Luigi) in 1409, drove away Genovese allies of Sardinians and subjugated a vast number of Sardinian nobles.
Split into simpler sentences: King Martin sent his son Martin the Younger to reconquer Sardinia. Just before his death, the son won the battle of Sanluri (San Luis, San Luigi) in 1409, drove away the Genoese allies of the Sardinians, and subjugated a vast number of Sardinian nobles.