Overextended - it derives from the efforts of the Allied armies in 1944 when they attempted to take a significant amount of land in Holland from the Germans. The initial efforts went very well, causing the Allies to become overly optimistic. When the German's counterattacked the Allies were too spread out to hold the ground they had taken and were subsequently driven back to where they started from.
See also Catastrophic Success, Scale Free Networks, Schwerpunkt and sit rep.
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