From 1810 to 1812 Saxony, Württemberg, Prussia and Bavaria founded a rural police force after the model of the Napoleonic French Gendarmerie.

Preußischer Landgendarm der XI. Gendarmerie-Brigade Kassel

The Prussian Gendarmerie staff (Königlich Preußische Landgendarmerie; Royal Prussian State Gendarmerie) were well-proven infantry and cavalry NCOs after serving their standard service time at the army and some COs. Officially they were still military personnel, equipped and paid by the Ministry of War, but in peacetime attached to the Ministry of the Interior, serving as normal or as mounted police. In case of a maneuver, mobilization or war 50% of the Gendarmerie formed the core of military police of the army, called Feldgendarmerie. Should more manpower be needed, regular infantry and cavalry corporals and some COs were seconded to the Feldgendarmerie under supervision of the former Gendarmerie NCOs/COs. The uniform of the Feldgendarmerie was identical with the uniform of the Landgendarmerie.

Deutsche Feldgendarmerie in Neu-Sandec Frühjahr 1915

At the outbreak of the First World War the Feldgendarmerie comprised 33 companies. They each had 60 men and two NCOs. By 1918, the number of companies had been expanded to 115 units.

After World War I, all military police units were disbanded and no police units existed in the inter-war Weimar Republic era. Garrisons were patrolled by regular soldiers performing the duties of the military police.

Feldgendarmerie units were generally given occupation duties in territories directly under the control of the Wehrmacht. Their duties policing the areas behind the front lines ranged from straightforward traffic control and population control to suppression and execution of partisans and the apprehension of enemy stragglers.

When combat units moved forward out of a region, the Feldgendarmerie role would formally end as control was then transferred to occupation authorities under the control of the Nazi Party and SS. But Feldgendarmerie units are known to have assisted the SS in committing war crimes in occupied areas. Author Antony Beevor explores some well-documented cases of their participation in his book Stalingrad. Also, Felgendarmerie units took active part in Jew hunting operations, including in Western Europe.

But by 1943 as the tide of war changed for Nazi Germany, the Feldgendarmerie were given the task of maintaining discipline in the Wehrmacht. Many ordinary soldiers deemed to be deserters were summarily executed by Feldgendarmerie units. This earned them the pejorative Kettenhunde (English: chained dogs) after the gorget they wore with their uniforms. The arbitrary and brutal policing of soldiers gave them the other nickname Heldenklauer (English: hero-snatcher) because they screened refugees and hospital transports for potential deserters with orders to kill suspected malingerers. Rear-echelon personnel would also be checked for passes that permitted them to be away from the front.

Feldgendarmerie guard a food truck in the Netherlands in 1945.

The Feldgendarmerie also administered the Strafbattalion (English: Penal Battalion) which were Wehrmacht punishment units created for soldiers convicted by court martial and sentenced to a deferred execution. During the final days of the war, as the Third Reich crumbled, recruits or soldiers who committed even the slightest infraction were sent to Strafbatallione.

Like many other elements of the German Army, the Feldgendarmerie was involved in the Holocaust. For instance, in August 1942 Feldgendarmerie units rounded up Jews in the Occupied Zone of France as part of a mass deportation operation. The Oxford Handbook of Holocaust Studies states that there is a need for further research into the role of the Feldgendarmerie during the Holocaust.

The SS-Feldgendarmerie wore the same uniform and gorget as their Army counterparts but had an addition cuff title indicating they were military police. Generally they conducted the same policing role, such as controlling rear areas but they also conducted counter-insurgency and extermination operations with Einsatzgruppen against Jews, partisans and those deemed to be "enemies of the Reich". These SS units had a severe reputation for being strict enforcers of military law. Nicknamed Kopf Jäger (Head Hunters), they also tracked down and punished those deemed to be deserters. From 1944 onwards, former members of the Ordnungspolizei serving with the Waffen -SS, were also given military police powers and duties. These special SS-Feldgendarmerie were denoted by a diamond polizei-eagle insignia worn on the lower sleeve.

In January 1944 as the Red Army began to advance on the Eastern Front, the power of the Feldgendarmerie was superseded by the creation of the Feldjägerkorps. Answering only to the German High Command (OKW), its three regiments were founded to maintain discipline and military cohesion in all branches of the Wehrmacht (including the Feldgendarmerie). Feldjägers were recruited from decorated, battle-hardened officers and NCOs. They had the military authority of the OKW to arrest and execute officers and soldiers from either the Wehrmacht or the SS for desertion, defeatism and other duty violations. Every unit of the Feldjäger had command of a "Fliegendes Standgericht" (flying drumhead trial/flying court martial), which comprised three judges.

Despite the surrender of all German forces in May 1945, some Feldgendarmerie and Feldjägerkorps units in the western zones of occupied Germany were allowed to keep their weapons by the Allies because of the number of POWs that required guarding and processing. For example, the British VIII Corps based in Schleswig-Holstein used an entire regiment of volunteers from the Feldgendarmerie to maintain discipline at its demobilisation center at Meldorf. Re-activated military police, who received extra rations as pay, were identified by an armband stating Wehrmachtordnungstruppe (Armed Forces Order Troop). In June 1946, more than 12 months after the official end of World War II, the Feldgendarmerie became the last German units to surrender their arms.