A commander's ability to leverage operational intelligence remains a cornerstone for managing the uncertainty, fog, and friction of war in this era of seemingly endless advances in battlefield awareness and information dominance. Operational intelligence, properly understood and utilized, can become a force multiplier maximizing traditional operational art factors. The goal is information superiority thereby increasing the speed at which decisions are made, while preempting enemy choices and courses of action. The challenge for the intelligence practitioner is not new. Indeed, WWI provides insights into how contemporary military commanders resemble their counterparts from nearly a century ago. The Battle of Tannenberg and Masurian Lakes, Russia's 1914 thrust into east Prussia as an opening salvo of WWI, was a disastrous defeat for Moscow due to German masterful leveraging of operational intelligence. German exploitation of intelligence from Signals, Human, and Imagery vis-à-vis aircraft observation, enabled them to crush the Czar's forces. The story of Tannenberg is a showcase of German successes to gain intelligence about the enemy while denying the Russians the same opportunity. Moreover, German commanders remained receptive and flexible, rapidly incorporating operational intelligence into tactical decision making. The reverse was true for the Russians. Operational intelligence, and the courage and flexibility to incorporate it into tactical and strategic plans, can help commanders manage the enigmatics of war. It worked for the German army in 1914 and can work on today's technologically advanced battlefield.