A: Pickett's division was only one of several Confederate units ordered to attack that day. To understand why Picketts charge was ordered, you have to understand the larger picture.

The reason for Robert E. Lee's campaign against the North at this time in the war was his desire to follow up his victory at Chancellorsville with a successful invasion far enough into the North that the northern politicians would be convinced to give up their support of the war. In other words, he hoped to destroy their morale and their will to fight by gaining so much ground that they would think their cause hopeless.

His advance into the north was stopped at Gettysburg where a fierce battle took place over three days. On the third day, Lee hoped to finally win the battle. He ordered the union lines bombarded with cannonfire and then 12,000 confederate troops were to charge across the open field.

Picketts charge was just one part of that attack, but has gained historical significance due to the 50% loss of Confederate soldiers, including nearly all the officers who participated that day.