 McClellan continued to believe intelligence reports that credited the Confederates with two or three times the men they actually had . Early in the campaign , Confederate General John B. " Prince John " Magruder defended the Peninsula against McClellan 's advance with a vastly smaller force . He created a false impression of many troops behind the lines and of even more troops arriving . He accomplished this by marching small groups of men repeatedly past places where they could be observed at a distance or were just out of sight , accompanied by great noise and fanfare . During this time , General Johnston was able to provide Magruder with reinforcements , but even then there were far fewer troops than McClellan believed were opposite him . 
