The history of our own war shows that an attack against the front and rear of a force is not necessarily fatal.

Baird's division at Chickamauga defended itself successfully against an assault of this kind, and Hancock faced his division both ways at Chancellorsville and repelled every attempt to force his position.
But Hooker thought otherwise.

He felt certain that if Sedgwick assailed Lee in rear, while he advanced in front, the Confederate army was doomed.

When the time came, however, to carry out this programme, if we may use a homely simile borrowed from General De Peyster, Hooker did not hold up his end of the log, and the whole weight fell upon Sedgwick.
About this time a pillar of the Chancellorsville House was struck by a cannon-ball, and Hooker, who was leaning against it at the moment, was prostrated and severely injured.

He revived in a few minutes, mounted his horse and rode to the rear, but it was some time before he turned over the command to Couch, who was second in rank.