Nugiseks was revered by many who maintain Estonians donned Nazi German uniforms only as a proxy for the already-disbanded national forces. He was one of four Estonian recipients of the Knight's Cross, the Third Reich's highest award for battlefield bravery, and partly because his decoration was captured on newsreels at the time, he became the best-known among them.

He avoided mobilization in the Red Army in 1941 and joined the Germans as a volunteer in the late summer, later becoming a volunteer in the 20th Waffen Grenadier Division of the SS.

Reunions of veterans of the unit, which was involved in last-stand fighting on the eastern front in 1944, have drawn criticism during the post-1991 independence period because of what has been seen as the government's imprimatur. Successive Estonian governments have said they honor all war veterans equally, whether they fought in Stalin or Hitler's forces, and have also been criticized by Estonian Legion veterans groups who say Nugiseks and his comrades were ignored.   

Nugiseks was wounded in late 1943 but returned to combat in February 1944 near Pskov, where he played the leading role in a capture of a bridgehead. He became a prisoner of war and was deported to Siberia, from which he returned in 1958.

After the restoration of independence, he was given honorary captain rank by the Defense Forces, and received a Defense League cross and a civic initiative medal of gratitude.