Complex sentence: After Mississippi repudiated her state bonds, Prentiss, who had earnestly opposed this action, moved to New Orleans in 1845, where he was leader of the bar, and prominent in philanthropic work.
Split into simpler sentences: After Mississippi repudiated her state bonds, Prentiss, who had earnestly opposed this action, moved to New Orleans in 1845. There he was leader of the bar, and prominent in philanthropic work.