Mezue ahịrịokwu na-esonụ: Na 30 Septemba, "Gruppe" kwagara n'ọdụ ụgbọelu dị na Uetersen, na-efe ozi nchekwa na German Bight. Ngalaba ahụ kwagara ọtụtụ oge ma na-efe efe na nchekwa nke Reich site na Esbjerg na 10 Mee 1940, mmalite nke Agha France. N'abalị iri na anọ nke ọnwa Mee, I. ((Jagd) "Gruppe" zigara Essen-Mülheim maka ọrụ megide France. N'ụbọchị 23 nke ọnwa Mee, a kpọghachiri ha ọzọ, nke ugbu a gaa Ferme Montecouvez, ebe ụgbọelu dị n'ebe ndịda Cambrai. Mgbe ụbọchị abụọ gachara, I. ((Jagd) "Gruppe" ka e nyere ọrụ inye ndị agha German ụgbọ njem na-ebugharị ndị agha nke anọ na nso Cambrai. N'ime ọrụ a, Clausen kwuru na "Armée de l'air" Potez 63 ụgbọ elu ejima ejima dara. N'oge a zutere, Messerschmitt Bf 109 E ya merụkwara, na-ebute ọdịda na nso Cambrai. Na 15 June, I. ((Jagd) "Gruppe" kwagara Saint-Omer, nke dị n'etiti
E bịanyere aka na nkwekọrịta agha na 22 June, na-akwụsị Agha nke France na 25 June. E nyere ndị otu ahụ ezumike ụbọchị atọ, e zigara ụfọdụ ndị ọkwọ ụgbọelu ezumike n'ụlọ. N'ụbọchị iri atọ n'ọnwa Juun, I. ((Jagd) "Gruppe" gbara ọsọ ka ha gbochie ụgbọ elu nke Royal Air Force Bristol Blenheim bombers nke butere ọgụ na ndịda ọdịda anyanwụ nke Saint-Omer. N'okwu a, Clausen kwuru na Blenheim si No. 110 Squadron gburu nke a na-ekwenyeghi ma e gburu ya na Bf 109 E. E nyere Clausen Iron Cross 1st Class () na 4 July 1940 ma bulie ya "Oberleutnant" (onye isi nke mbụ) na 1 February 1941. N'ụbọchị ahụ, a họpụtara Clausen ka ọ bụrụ "Staffelkapitän" (onye isi ndị agha) nke 1. "Staffel" nke "Jagdgeschwader" 77 (JG 77<unk>77th Fighter Wing) na 6 Jenụwarị 1942.