Overcome By Events or Overtaken By Events (OTBE), is a term of military origin used when a situation changes so rapidly that previously proposed courses of action are no longer relevant.

Examples

An example for OBE, albeit in a political context, would be the changes in foreign politics

Foreign policy

A country's foreign policy, also called the foreign relations policy, consists of self-interest strategies chosen by the state to safeguard its national interests and to achieve its goals within international relations milieu. The approaches are strategically employed to interact with other countries...

 due to the unexpected event of the September 11, 2001 attacks

September 11, 2001 attacks

The September 11 attacks The September 11 attacks The September 11 attacks (also referred to as September 11, September 11th or 9/119/11 is pronounced "nine eleven". The slash is not part of the pronunciation...

 

In a military context, the first use of the atomic bomb on Japan probably caused the Japanese government to be OBE.