As a member of I./JG 76 Philipp saw action over Poland and scored his first victory on 5 September 1939, a Polish P.24 seven km southwest of Radomsko. Later during the Battle of Britain, Hans Philipp was appointed Staffelkapitan of 4./JG 54 and soon gained a reputation for being a superb dogfighter, often preferring to battle it out with enemy fighters rather than bombers.

Philipp's successes in combat were recognized on 4 November 1940 when he was awarded the Knights Cross for his twenty victories to date. On 14 November he reached a total of 23 victories by downing a Hurricane over Canterbury. Thereafter he participated in the Balkan Campaign where "Fips" would add another two Abschüsse on 7 April by shooting down two Yugoslavian Bf 109 "Emils".

His first VVS aircraft shot down was a SB-2 bomber downed northwest of Kossowo on the first day of Unternehmen Barbarossa. On 24 August 1941, Philipp became the 33rd member of the German Armed Forces to be awarded the Oak Leaves to the Knights Cross. When Franz Eckerle, the Kommandeur of I./JG 54, was posted missing on 14 February 1942, Hans Philipp was chosen as his successor.

As the new Kommandeur he oversaw the early careers of many young fighter pilots, among them Walter Nowotny. Three days later on 17 February 1942, he would score his first victory as the new Kommodore. During this winter period, like most Luftwaffe units, I./JG 54's mission objectives were hampered by the low number of aircraft available. This problem must have been the first priority of Philipp as the new boss to solve. Otherwise, as a fighter pilot, he followed the classic maxim by the famous WWI ace Manfred von Richthofen; "...find your enemy and shoot him down - everything else is unimportant."

As a consequence, on an early morning mission with his wingman Uffz. Gerhard Proske, both pilots manage to bag one I-18 (MiG-3) each; Philipp thus reached 79 confirmed victories and Proske his 10th. There then followed two more I-18s for the Kommodore, one on the 19th and a second on 22 February. He soon added another five Abschüsse, the last one being an I-18 filed on 28 February, bringing Hptm. Philipp to 86 confirmed victories.

In recognition of his accomplishments, on 12 March 1942 he received the Swords to the Knight Cross. Another milestone in his career was achieved on 31 March when Philipp became the fourth Luftwaffe fighter pilot to achieve 100 victories by claiming two Soviet flown Curtiss P-40 fighters. By this time the Gruppe was strengthened through the receipt of an additional 12 Bf 109 F-2s thereby reaching 32 fighters, close to the establishment number.

Philipp's Bf 109 F-2 sports a uniform overcoat of temporary water-based white paint over its entire top and side surfaces, but leaving the lower part of the yellow Ostfront theatre markings bare. It also displays the I. Gruppe and Geschwader insignias on both sides of the fuselage. On the rúdder one could also see the Swords of the Ritterkruetz painted on.