A Saint-Cyrien from the class of Lieutenant Tom Morel (1987-1990), Lieutenant General Cottereau chose to serve in the armoured cavalry at the end of his studies.
In 1991, he was assigned to the 4th Dragoon Regiment as a platoon leader, during which time he was deployed Yugoslavia with the United Nations Protection Force in the former Yugoslavia. Upon promotion to Captain in 1994 he was posted to the Cavalry School in Saumur as an instructor. In 1996, he joined the 1st Spahis Regiment in Valence to command the 3rd armoured reconnaissance squadron. In 1998, he became a staff officer in charge of instruction and operational training.
From 1999 to 2001, he served at the Institut des Hautes Etudes de Défense Nationale (IHEDN) and was promoted to Major in 2000. In 2001, he attended the 115th class of the Cours Supérieur d'Etat-Major (CSEM) and in 2002, he joined the 10th class of the Collège Interarmées de Défense (CID, nowadays called Ecole de Guerre/War College).
In 2003 he was appointed head of the Operations and Training Office of the 2nd Hussard Regiment, a land forces HUMINT regiment. Promoted to Lieutenant Colonel in 2004, he was deployed to Kosovo in 2005 as commander of the multi-sensor intelligence unit of the Multinational Brigade North-East. In 2005 he was appointed Military Assistant to the General Commanding Army Training. In 2007 he was seconded to the French Ministry of Foreign Affairs as Deputy Director of the Southern Europe Department and was promoted to Colonel in 2008.
From 2009 to 2011 he commanded the 2nd Hussard Regiment. During this period, he deployed regimental personnel to Chad, Kosovo, Afghanistan and Lebanon. From 2011 to 2013 he served in the office of the Supreme Allied Commander Transformation (SACT) in the United States where he was a Special Assistant, the Director of the Commander's Action Group and the Chief of the Office of Studies.
In 2014 he joined the General Secretariat for Defence and National Security (SGDSN) as Deputy Director for International Affairs. In this interministerial role he provided studies and support to the political decision making process within the framework of defence councils, terrorist threat assessment, NATO ballistic missile defence strategy, crisis response plans, intelligence issues in connection with the national intel advisor, Sahel-Saharan regional strategy and interministerial strategic anticipation.
From 2016 to 2018 he was assigned to the Planning and Conduct of Operations Center (CPCO) in Paris as Chief JS and Deputy Planning and Logistics.
Promoted Brigadier General on July 1, 2018, he was deployed to Bamako, Mali, as Chief of Staff of the United Nations Multidimensional Integrated Stabilisation Mission in Mali force. From 2019 to 2021, he was the deputy commander of the 3rd US Infantry Division at Fort Stewart, Georgia. He participated in 3 Warfighter exercises (including one as an US Corps Commander) and 12 divisional exercises. He led the division's evacuation operations in response to Hurricane Dorian, the COVID response for the military and civilian personnel (including families) at Fort Stewart, and the preparation and deployment of three US brigades for overseas operations.
He was promoted to Major General on May 7, 2021. On July 17, 2021 he assumed command of the 3rd Division, whose headquarters is in Marseille.
On Sep 1, 2022, he was promoted to Lieutenant General and assigned as Vice Chief of Staff Supreme Headquarters Allied Powers Europe.