The converging artillery fire from the batteries, they reasoned, could distress the Federals to the point that an infantry assault by McClellan's forces would open up the Union line, allowing Lee's soldiers to break through and attack.
The converging artillery fire from the batteries, they reasoned, could distress the Federals to the point that they were forced to assault the grand battery positions with infantry. An infantry assault by McClellan's forces would open up the Union line, allowing Lee's soldiers to break through and attack.