Why did Hermann von Helmholtz serve as an army doctor after medical school?

Hermann von Helmholtz served as an army doctor because he received his medical education at the Friedrich Wilhelm Medical Institute in Berlin under the condition that he commit to eight years of service as a military physician.1

He began this service in 1843 after graduating from medical school, where he was assigned to a regiment in Potsdam. Because his military duties were relatively light, he was able to conduct scientific experiments in a makeshift laboratory within the barracks. His clear scientific talent eventually led to his release from these military obligations before the full eight-year term was completed, allowing him to pursue his academic and research career.1