When the Tet offensive occur?

1. Cause-underestimation of the enemy. 2. Consequences-War was unwinnable. Reason war was unwinnable: Without widening the war into the neighboring countries of Laos and Cambodia, which was the communist infiltration routes (Ho Chi Minh Trail specifically); and risking a confrontation with the communist superpowers (Soviet Union & Red China-which DID occur in the Korean War) it was time to either fish or cut bait; we cut bait.