Overcome By Events
Overcome By Events (OBE) (or Overtaken By Events), is a term of military origin used when the initial solution to a problem is rendered useless by unexpected events, raising a need for a different solution.
Examples
An example for OBE, albeit in a political context, would be the changes in foreign politics due to the unexpected event of the September 11, 2001 attacks
In a military context, the first use of the atomic bomb on Japan probably caused the Japanese government to be OBE.
Usage at the United States Marine Corps
To the U.S. Marines, this phenomenon is known as "The 80% solution"; this is a reference to the success rate for the replacement solution. This replacement solution is based on a rational, yet profitable plan. Any effects observed during the post-implementation phase of the 80% solution often render other considered solutions obsolete.