New mapping shows Lee could not see depth of union forces at Gettysberg

Smithsonian Magazine:

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Altogether, our mapping reveals that Lee never had a clear view of enemy forces; the terrain itself hid portions of the Union Army throughout the battle. In addition, Lee did not grasp – or acknowledge – just how advantageous the Union’s position was. In a reversal of the Battle of Fredericksburg, where Lee’s forces held the high ground and won a great victory, Union General George Meade held the high ground at Gettysburg. Lee’s forces were spread over an arc of seven miles, while the Union’s compact position, anchored on several hills, facilitated communication and quick troop deployment. Meade also received much better information, more quickly, from his subordinates. Realizing the limits of what Lee could see makes his decisions appear even bolder, and more likely to fail, than we knew.

Check out the interactive map at the link above.  I would also add that the machinery of warfare had given the defensive an advantage that was to last through the early days of World War I.  The repeating rifles made cavalry attacks ineffective and disastrous.  It is a point that Stonewall Jackson grasped early in the war, but he had been killed in a friendly fire incident before this battle.  Jackson was also good a maneuver warfare.  It was an art that few Civil War generals mastered.

The machinery of war had rendered combined arms attacks ineffective and the results was carnage on a grand scale on both sides.  It still remains the most costly war in US history.  Late in World War I the introduction of tanks and aircraft restored the combined arms concept replacing both heavy and light cavalry.  By World War II combined arms attacks were common during German offensives, and were later used by US forces in defeating Germany.