Lieutenant Colonel Chelsey O’Nan

Deputy Commander

U.S. Army Corp of Engineers - Japan Engineer District
Published March 10, 2021

Lieutenant Colonel Chelsey O’Nan commissioned as an Engineer Lieutenant in 2007 after graduating from the United States Military Academy.  Following Officer Basic Course, she served as a platoon leader with 161/27th EN BN.  As a Light Equipment (LE) Platoon Leader, she had the opportunity to participate in an Airborne Assault Joint Forces Exercise at Ft. Irwin, California.  After air-dropping four vehicles, four equipment boxes, and 30 Soldiers into Ft. Irwin, they conducted 24 hour operations to fix and maintain the 4000 meter runway.  Their efforts enabled over 40 successful air lands during the exercise and provided Ft. Irwin with an operational runway following the departure.  After her platoon leader time, she transitioned to the 161st Company Executive Officer position where she prepared and accompanied the company on a 12-month deployment to Afghanistan in support of Route Clearance Operations.

Following her time with 161st ESC, she assumed command of the 27th EN BN Rear-Detachment.  She served seven months as the Rear-Detachment Commander working with families, spouses, one LARP platoon, and numerous injured Soldiers that returned from Afghanistan.  During the deployment, the unit lost 13 Heroes, and she had the humbling and rewarding opportunity to work with each one of the families following their loss. 

LTC O’Nan completed the Engineer Captain’s Career Course in December 2011 and received her master’s in engineering management from Missouri Science and Technology in May 2012.  After a brief time as the Training Officer for the 65th EN BN, MAJ O’Nan assumed command of HHC/65th EN BN.  During her command, she had the privilege to serve and deploy with 118 Soldiers on a nine-month deployment to Afghanistan.  While in theater, the Battalion commanded eight National Guard and Reserve Companies spread across three different Regional Commands (RC).  

She successfully relinquished command of HHC/65th EN BN in May 2014 before redeploying to Schofield Barracks, HI and preparing to transition to the USACE team.  LTC O’Nan served her first USACE assignment with Louisville District as an executive officer and project engineer for the Olmsted Lock and Dam, an innovative construction project and true engineering marvel.  Their project received the attention of congressional staff members and senior level officers in both the Army and Coast Guard.

Following her time with Louisville District, she earned her second master’s degree in business administration through the University of Colorado, Denver before completing ILE, and transitioning to the Transatlantic Middle East District (TAM) as the Program Manager (PM) Forward for the Kuwait Resident Office at Camp Arifjan.  As a PM Forward, she worked closely with USARCENT and USAFCENT on $1.1 Billion in active construction contracts to deliver enduring, high-quality infrastructure to both the U.S. and Host Nation militaries.

After completing her time with TAM, LTC O’Nan served as both the Battalion S3 and Battalion Executive Officer for the 27th Engineer Battalion at Ft. Bragg before moving up to S3 HHBN, 18th Airborne Corps.  During this time, she served as the Outload Support Battalion OIC for the no-notice outload of the 82nd Airborne in January 2020, ensuring 4,500 Paratroopers, 360 vehicles, and 342 containers deployed on over 100 aircraft in less than a month.  She also played a key role in the 82nd Airborne outload for HKIA by overseeing 700 Outload Support Exercise (OSE) personnel and supporting the arrival and departure of 3,500 Paratroopers and 200 pieces of rolling stock through the Life Support Area in less than a week.  Before concluding her time at Ft. Bragg, LTC O’Nan outloaded the Corps Headquarters in support of the ongoing War in Ukraine.  She served as the senior Battalion representative forward in Germany, overseeing the life support area for the Corps Staff and multiple attached units.

Assuming the Deputy Commander position at the U.S. Army Corps of Engineers – Japan Engineer District, she helped steer a more than 2-billion-dollar program out of the troubled waters of the COVID pandemic in a country that had closed itself off to the world for three years prior 3. Promoted to the rank of LTC in April 2023, she continues to serve the Japan District with honor, grace, and dignity.

Her awards and decorations include the Bronze Star Medal, Meritorious Service Medal (3), Army Accommodation Medal (3), German proficiency badge, and German jump wings.

Her parents, sister, brother-in-law, and niece all reside in LTC O’Nan’s home state of Colorado and continue to provide unwavering support from afar. 



日本地区本部  副司令官   



チェルシー・オーナン中佐は、2022年7月に米国陸軍工兵隊日本地区(JED)の副司令官に就任した。同中佐の前職は、2020年から2022年までノースカロライナ州フォートブラッグの第18空挺軍団本部大隊参謀(S3 HHBN)であった。

オーナン中佐は、米陸軍士官学校を卒業、2007年に工兵中尉に任官した。士官基礎課程の後、同氏は第27工兵大隊・第161工兵支援中隊(161/27th EN BN)で小隊長を務めた。この軽装備小隊の隊長として、カリフォルニア州フォートアーウィンで行われた空挺強襲統合部隊演習に参加する機会を得た。第161工兵支援中隊の副隊長へ異動後、不朽の自由作戦を支援するため、12カ月間の同中隊アフガニスタン派遣を準備し、これに同行した。


同中佐は、第161工兵支援中隊での勤務に引き続き、第27工兵大隊後方分遣隊(27th EN BN Rear-Detachment)を指揮した。また、後方分遣隊長として軍人家族、配偶者、滑走路修復小隊及びアフガニスタンから帰還した多数の負傷兵などの対応に7カ月間勤務した。


オーナン中佐は、2011年12月に米陸軍工兵大尉職務課程を修了し、2012年5月にミズーリ工科大学から技術管理工学修士号を取得した。第65工兵大隊の訓練士官として短期勤務した後、同中佐は第65工兵大隊本部中隊(HHC/65th EN BN)を指揮した。この期間中、アフガニスタンへ9か月間派遣される3つの米軍地域コマンドからの兵士118人と共に現地へ派遣され、指揮する機会に恵まれた。




ルイビル地区勤務の後、同氏はコロラド大学デンバー校で2つ目の修士号である経営学修士を取得し、士官中級課程(ILE) を修了した。その後、工兵隊大西洋中東地区(TAM) へ異動し、前方プログラムマネージャーとしてクウェートのキャンプ・アリフジャン事務所で勤務した。そこでは、米国及び受入国の両軍隊に高品質のインフラを永続的に提供するため、継続中の11億ドル建設契約について米中央陸軍及び米中央空軍と緊密に協力して進めてきた。


工兵隊大西洋中東地区で勤務後、同中佐はノースカロライナ州フォートブラッグで第27工兵大隊の参謀及び副隊長を勤めた。その後、第18空挺軍団の本部大隊参謀(S3 HHBN)へ昇格した。この期間中、2020年1月の第82空挺軍団のへの予定外輸送作業に対する輸送支援大隊担当士官を務め、1カ月足らずで100機以上の航空機によって4500人の空挺部隊、360台の車両、342個のコンテナが確実に展開できるよう努力した。また、同氏は第82空挺軍団のカブール国際空港(HKIA)向け輸送の際、輸送支援演習(OSE)要員700人を監督すると共に、1週間足らずで宿営地に到着・出発する空挺部隊3500人と車両200台の輸送を支援する重要な役割を果たした。フォートブラッグでの勤務を終える前、オーナン少佐は現在進行中のウクライナ戦争を支援するため、軍団本部の輸送任務に従事した。同氏は、ドイツにおける前方大隊上級代表として、軍団参謀及び複数の付属部隊用の宿営地を監督した。