Player Embed Code: Download Embed Share Secretary, Joint Chiefs Chairman Testify at House Committee Hearing, Part 1 Defense.gov April 12, 2018 | 01:54:46 Defense Secretary James N. Mattis and Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, testify at a House Armed Services Committee hearing on the Defense Department's fiscal year 2019 budget and posture, April 12, 2018. Part 1 of 2.