Victory disease occurs in military history when complacency or arrogance, brought on by a victory or a series of victories, makes an engagement end disastrously for a commander and his forces.[1]
A commander may disdain the enemy, and believe his own invincibility, leading his troops to disaster. That commander may employ strategies that, if effective in earlier combats or maneuvers, prove catastrophic against a new or smarter enemy. The commander afflicted by "victory disease" may also fail to anticipate that a new enemy may use tactics different from those of old enemies. An overconfident commander may disregard military intelligence that would enable the commander to realize that new tactics are needed.
Though "victory disease" does not inevitably foretell defeat, it often precedes it. The term is also applied outside the military world in areas such as psychology, business, or marketing.