O'Neill was the representative for Ohio's 13th congressional district and was a Democrat. He served from 1863 to 1865.
From Dec 1863 to Mar 1865, O'Neill missed 194 of 600 roll call votes, which is 32.3%. This is on par with the median of 28.2% among the lifetime records of representatives serving in Mar 1865. The chart below reports missed votes over time.