Warrant Officer Class One Paul Holstein enlisted into the Regular Australian Army on 27 June 1984. On completing recruit training, he was allocated to The Royal Regiment of Australian Artillery and completed initial employment training at the School of Artillery. He was then posted to A Field Battery, 8th/12th Medium Regiment. During his posting to the 8th/12th Medium Regiment, he progressed through the ranks and was promoted to Sergeant in late 1991.

In January 1992, he was posted to 108th Field Battery, 4th Field Regiment as a sergeant detachment commander. In 1996, he was posted to the School of Artillery, as an instructor at the Regimental Training Wing. In June 1998, he deployed on Operation MAZURKA as a member of the Multinational Force and Observers, Sinai Egypt, as the Force Operations Sergeant.

In 1999, he was posted to the 103rd Medium Battery, 8th/12th Medium Regiment. In August that year he was promoted to Warrant Officer Class Two and posted to 7th Field Battery, as the Sergeant Major Instructor Gunnery.

In January 2002, Warrant Officer Class One Holstein was posted to the Royal Military College – Duntroon as a company sergeant major and in 2004, the Operations Warrant Officer. In 2005, Warrant Officer Class One Holstein was posted to the Australian Defence Force Academy as a squadron sergeant major. In 2007, Warrant Officer Class One Holstein was posted to the Directorate Personnel and Capability – Army, Employment Management Section as the Warrant Officer Employment Management.

In January 2008, Warrant Officer Class One Holstein was posted to the 20th Surveillance and Target Acquisition Regiment as a battery sergeant major. In 2009, he deployed to Timor-Leste on Operation ASTUTE as the Company Sergeant Major, Headquarters JTF631.

In 2010, he was promoted to Warrant Officer Class One and appointed the Regimental Sergeant Major, 2nd/10th Field Regiment. In 2012, he deployed to Afghanistan on Operation SLIPPER as the mentor to the 205th Corps Command Sergeant Major and Regimental Sergeant Major 205th Coalition Advisory Team. In 2013, Warrant Officer Class One Holstein was posted to 1st Regiment, RAA as the Master Gunner and in 2014, was appointed the Regimental Sergeant Major.

His honours and awards include the Australian Active Service Medal with ICAT Clasp, Afghanistan Medal, Australian Service Medal with Clasp Sinai and Timor-Leste, the Defence Long Service Medal with Second Clasp, Australian Defence Medal, Multinational Force and Observers Medal, Timor-Leste Solidarity Medal, NATO Medal with ISAF clasp, United States Army Commendation Medal and the Army Combat Badge.

Warrant Officer Class One Holstein was awarded a Commander 2nd Division Commendation in 2002 for exemplary duty as the Sergeant Major Instructor Gunnery, 7th Field Battery, Commander Australian Defence College Commendation in 2006, for his performance as a squadron sergeant major at the Australian Defence Force Academy and in 2013, Deputy Chief of Joint Operations Commendation for his achievements as a mentor to the 205th Corps Command Sergeant Major and Regimental Sergeant Major 205th Coalition Advisory Team.