After studying first mathematics and then engineering at the École Polytechnique, Cauchy was initially employed as an engineer. However in 1815 he was appointed to the faculty of the École Polytechnique to teach mathematical analysis. Despite his many publications, he was not promoted to full professor for 18 years because he refused to take the oath of allegiance to the republican government. He made major developments in the theories of determinants (see matrix), partial differential equations, group theory, and complex variables. His last words were said to be ‘Men pass away—but their deeds abide’. He was elected FRS in 1832 and FRSE in 1845. A street in Paris and a lunar crater are named after him.

http://scienceworld.wolfram.com/biography/Cauchy.html Fuller biography and portrait.