 On 15 July the Twenty-Eighth Army, despite the mistiming of the Thirty-third Army's attack, began their break-out attempt, unaware that the British knew of their plans.The monsoon had begun and the British created two killing fields, the first for artillery (targeting twelve Japanese crossing points along the highway) and the second using aircraft (which were able to fly even in poor weather conditions) to attack those who managed to cross the road, especially between the Sittang and the Salween rivers.FOOs were used in the air and the ground.