Nehemiah, son of Hacaliah, was a cupbearer of the Persian King Artaxerxes. In 444 B.C. the king appointed Nehemiah to be the governor of Judah and permitted him to go to Jerusalem to help his fellow Jews. He rallied the people to rebuild the damaged walls around Jerusalem (Neh 2:17).
Despite opposition from his enemies, Sanballat and Tobiah, he succeeded in rebuilding the walls in 52 days and stationed guards at the city gates. In order to repopulate Jerusalem he ordered that one out of every 10 Jews should take residence in Jerusalem (Neh 3-6).
He also instituted a series of social reforms including the cancellation of debts owed by the poor and the payment of tithes, he then returned to Persia. In 432 B.C., he came back to Jerusalem and enforced several laws (Neh 8-13), such as payment due to the Levites and the observance of the Sabbath (Neh 13:15-22).
The story of Nehemiah is found in the book of Nehemiah.