Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42.

The Battle of Gettysburg

One of the most important battles of the American Civil War occurred around the small town of Gettysburg, Pennsylvania, from July 1 to July 3, 1863. What began as a search for shoes by the Confederate Army quickly escalated into a major battle. As the Confederate soldiers sought new shoes, they unexpectedly encountered Union cavalry stationed west of the town at Willoughby Run, and the battle began. After much fighting and heavy casualties on both sides, the Confederates pushed the Union forces back through the town of Gettysburg, where they regrouped south of the town along the high ground near a cemetery.

Confederate General Robert E. Lee ordered General R.S. Ewell to seize the high ground from the

battle - weary Union soldiers "if practical." Ewell hesitated in the attack, giving the Union troops a chance to establish a stronghold along Cemetery Ridge and then bring in reinforcements with artillery. By the time Lee realized Ewell had not attacked, the opportunity had vanished. Other failures by the Confederates included the generals' opposition to the attack plans and a lack of information about Union defense. This combination of errors allowed the Union forces to win a critical victory in the Civil War. By the end, a total of 160,000 men were involved in this fierce and bloody battle.

Question 36: What is the main idea of the passage?