Who is Alexander from The Jewish War and what is their importance?

The first Alexander mentioned in the text was the son of John Hyrcanus. When John died, Alexander's oldest brother Aristobulus made himself monarch, placing his brothers out of the wat and in jail. Aristobulus died within a year, after which, his widow made Alexander monarch. Alexander executed one of his brothers but honored the only one left. He continued to acquire land until he died twenty-seven years later. Alexander left the throne to his wife Alexandra.