He commanded Attack Squadron 196 (VA-196) on board USS Independence in 1990-1991 during Operation Desert Shield and Carrier Air Wing Two at NAS Miramar, California and embarked on board USS Constellation in 1994-1995 during deployment to the Persian Gulf in support of Operation Southern Watch.

He commanded Carrier Group One headquartered at NAS North Island in San Diego, California from July 2000 until November 2001.

His naval assignments ashore include duty as an Operational Test Director in Air Test and Evaluation Squadron 5 (VX-5) at Naval Air Weapons Station China Lake, California; Tactics Department Head at the Naval Strike Warfare Center/Strike University at NAS Fallon, Nevada; Executive Assistant to the Deputy Assistant Secretary of the Navy — Tactical Programs in Washington, D.C.; Attack Readiness Officer at Medium Attack and Tactical Electronic Warfare Wing, U.S. Pacific Fleet (MATVAQWINGPAC) at NAS Whidbey Island, Washington.

VADM Nichols is a distinguished graduate of the United States Naval War College, Newport, Rhode Island, and a graduate of the National Defense University's Joint and Combined Staff Officer School at the Joint Forces Staff College, Norfolk, Virginia.

Following his retirement from the Navy, he has served as a Senior Mentor / Highly Qualified Expert to HQ USCENTCOM for periodic exercises, as an adjunct faculty member to the U.S.