Jeffrey later recalled chiding Jackson for his eagerness to return to combat despite having already done enough in the war, to which the latter replied, "What are you fighting for? King and country? Well, I'm fighting for my wife and kids and no Jap bastard's going to get them!" On 21 March, Jackson led the squadron's main force to Seven Mile Aerodrome to take part in the defence of Port Moresby, a crucial early battle in the New Guinea campaign, and what military aviation historian Andrew Thomas called "one of the most gallant episodes in the history of the RAAF". The unit was equipped with P-40 Kittyhawks, whose long-awaited arrival had seen them irreverently dubbed "Tomorrowhawks", "Neverhawks", and "Mythhawks" by the beleaguered garrison at Moresby. Jackson's age of thirty-four was considered advanced for a fighter pilot, and he was affectionately known as "Old John" to his men, one of whom was his younger brother Les, now a flight lieutenant. As CO, Jackson's leadership was to prove inspirational to his pilots, many of whom had received only nine days of training in fighter tactics, and fired their guns just once. On 22 March, the day after he arrived in New Guinea, Jackson took No. 75 Squadron on a dawn raid against the Japanese airfield at Lae. Rather than attacking directly from the south, he led the Kittyhawks in from the east, where they would not be expected and where the rising sun would hide their approach. Achieving the surprise he had hoped for, Jackson made two strafing passes over the airfield, ignoring standard practice that called for only one such pass to reduce the risk from anti-aircraft fire. The Australians claimed a dozen Japanese planes destroyed on the ground and five more damaged. They also shot down two Mitsubishi Zero fighters in the air, and lost two Kittyhawks over Lae, along with one that had crash-landed on takeoff from Moresby. The Japanese struck back the next day, destroying two Kittyhawks at Seven Mile Aerodrome. With his losses mounting, Jackson was given permission to withdraw the squadron to Horn Island in Far North Queensland, but refused. On 4 April, Jackson made a solo reconnaissance over Lae, after which he led another four Kittyhawks on a raid against the airfield, claiming seven enemy aircraft destroyed on the ground without loss to themselves; Japanese sources credited the Australians with only two machines destroyed, but seventeen others damaged.