On 9 April 1940 Nazi Germany invaded Norway, capturing ports along the Norwegian coast from Oslo to Narvik. The main field artillery piece of the Norwegian Army that faced the invasion forces was the Ehrhardt Model 1901. During the two months of fighting in the Norwegian Campaign that followed the Norwegian field artillery arm suffered greatly from organizational difficulties. The difficulties originated in part from the fact that very few artillery pieces had been mobilized during the seven months of neutrality that preceded the invasion. The units that had been activated to guard Norwegian neutrality had been equipped mainly with rifles and light and heavy machine guns. In the confusion and chaos that followed the German invasion most Norwegian units were only mobilized on an improvised basis, with limited supplies and little time to get properly organized before going into battle with the Germans. Only in Northern and Western Norway did the units (the 6th Division in Northern Norway and the 4th Brigade in Western Norway) have time to mobilize in an orderly fashion. Due to the complete lack of dedicated anti-tank guns in the Norwegian Army, Model 1901s were pressed into service in an improvised anti-tank role during the fighting in Eastern Norway. The field guns were used in direct fire mode at close range against German Panzers. All 12 of the Model 1901 field guns that had been converted to motorized transport were deployed to Northern Norway at the outbreak of war, with four in Troms County and eight in the eastern parts of Finnmark. Seven of these guns saw action on the Narvik front, supporting the Norwegian counter-offensive against Eduard Dietl's Gebirgsjägers.