圍魏救趙

In 354 BC, the state of Wei attacked Zhao and laid siege to(包圍) its capital Handan.

Zhao turned to Qi for help, but the Qi general Sun Bin determined it would be unwise to meet the army of Wei head on, so he instead attacked their capital at Daliang.

When the Wei general Pang Juan heard that the capital was being attacked, he rushed his army back to defend the capital. The army of Wei retreated in haste, and the tired troops were ambushed and defeated at the Battle of Guiling.

Zhao was thus rescued while Pang Juan barely escaped back to Wei to recoup(收回，恢復(fù)) his losses.