Successful military invasions require a significant advantage in both manpower and weaponry, specifically a three to one ratio for efficacy. The Germans faced challenges as they had fewer troops and inferior tank technology compared to the British, leading to doubts about their strategic plans. Additionally, the exploration of unconventional methods, such as the use of meth, illustrates how desperation can drive interest in controversial tactics. This highlights that in dire situations, even radical ideas can gain traction within military circles.