positions at the start of the invasion. The total strength of the Royal Yugoslav Army at full mobilization was about 1,200,000 however only around 50 per cent of the recruits were able to join their units before the German invasion. By 20 March 1941, its total mobilized strength amounted to 600,000. On the eve of the invasion, there were 167 Generals on the Yugoslav active list. Of these, 150 were Serbs, 8 Croats, and 9 Slovenes. The Royal Yugoslav Army was organized into three army groups and the coastal defense troops. The 3rd Army Group was the strongest with the 3rd, 3rd Territorial, 5th and 6th Armies defending the borders with Romania, Bulgaria and Albania. The 2nd Army Group with the 1st and 2nd Armies, defended the region between the Iron Gates and the Drava River. The 1st Army Group with the 4th and 7th Armies, composed mainly of Croatian troops, was in Croatia and Slovenia defending the Italian, German (Austrian) and Hungarian frontiers. The strength of each "Army" amounted to little more than a corps, with the three Army Groups consisting of the units deployed as follows; The 3rd Army Group's 3rd Army consisted of four infantry divisions and one cavalry detachment; the 3rd Territorial Army with three infantry divisions and one independent motorized artillery regiment; the 5th Army with four infantry divisions, one cavalry division, two detachments and one independent motorized artillery regiment and the 6th Army with three infantry divisions, the two Royal Guards detachments and three infantry detachments. The 2nd Army Group's 1st Army had one infantry and one cavalry division, three detachments and six frontier defence regiments; the 2nd Army had three infantry divisions and one frontier defence regiment. Finally, the 1st Army Group consisted of the 4th Army, with three infantry divisions and one detachment, whilst the 7th Army had two infantry divisions, one cavalry division, three mountain detachments, two infantry detachments and nine frontier defence regiments. The Strategic, "Supreme Command" Reserve in Bosnia comprised four infantry divisions, four independent infantry regiments, one tank battalion, two motorized engineer battalions, two motorized heavy artillery regiments, fifteen independent artillery battalions and two independent anti-aircraft artillery battalions. The Coastal Defence Force, on the Adriatic opposite Zadar comprised one infantry division and two detachments, in addition to fortress brigades and anti-aircraft units at Šibenik and Kotor. Along with other Yugoslav forces, the Royal Yugoslav Army surrendered on 17