In addition there is a pattern of evidence indicating that, for whatever reason, some Union generals may have deliberately lost certain battles or ignored certain military opportunities.
Major General George McClellan was a Democrat with some sympathy for the South, but he was a top notch military organizer, trainer, and inspirer of men, who restored Union morale and confidence...and then proceeded to fail on the battlefield over and over. After rebuilding the damaged Army of the Potomac, he led it in 3/62 to attack Richmond, Virginia, the Confederate capital. Rather than take the direct overland route, which offered the opportunity to bring the Southern armies to battle close to his supply bases, he transported his men by sea to land at Fort Monroe, Virginia, on the peninsula between the James and York rivers. It can be argued that this gave him a secure supply base and some flank protection, and avoided the more difficult river crossings of the overland route. But then he dawdled for an entire month at Yorktown while the Confederates prepared their defenses; by accident or design he ignored the obvious need for speed. Reportedly, McClellan believed the exaggerated reports of Confederate strength given to him by the Pinkerton Agency...despite the well-known Northern superiority in man power and industry.
On 5/31/62 the Confederates attacked him at Fair Oaks (Seven Pines), beginning the Battles of Seven Days. His forces drove them back, but failed to counter attack. Robert E. Lee took over the Southern armies and, ever agressive, attacked part of McClellan's forces under General Porter north of the Chicahominy River at Mechanicsville. Porter withdrew and Lee attacked him again on 6/27 near Gaines Mill, and Porter crossed the Chickahominy to join McClellan's main force. On 6/29 and 6/30 Lee attacked McClellan at Savage Station and Glendale, and McClellan's forces drove them off...and then retreated. He drove Lee off again at Malvern Hill, having over 100,000 troops to Lee's 85,000, but retreated again. Then he withdrew by sea from the peninsula. This beggars belief. With superior forces and secure supply, he won the battles and ran away. This seems to go far beyond mere incompetence.
Emboldened, Lee invaded Maryland with 55,000 men to McClellan's 90,000. He split his army into four main columns, but, via a strange accident, McClellan got a copy of Lee's battle orders. He now had an opportunity to attack part of the Confederate forces with most of his, crushing them by sheer firepower and practically ending the war. The need for immediate action would be obvious to a first year cadet at West Point...but not to McClellan. He got the copy of the orders on 9/13/62 but waited until late the next morning to begin a liesurely march to intercept the enemy; an overnight march would have succeeded. By the time McClellan attacked at Antietam Creek near Sharpsburg on 9/17, Lee had more of his forces ready and waiting, but McClellan still had a huge advantage.
He performed such acts of military genius as having Burnside try to cross a heavily defended bridge instead of wading the shallow creek, and attacking piecemeal with only parts of his 70,000 to 90,000 men. Using the well known "two up and one back" principle, he could have attacked with 50-60,000 men against Lee's 40,000. But that was not McClellan's way. Despite everything McClellan could do to snatch defeat from the jaws of victory, his men still virtually crushed the Confederates, though at a terrible cost, and he still had reserves. But he failed to finish Lee off, which would have saved lives in the long run, or even encircle and entrap him, and he let Lee withdraw on 9/18.
This was too much even for the long-suffering (or worse) Lincoln, and he replaced McClellan with Major General Ambrose Burnside, with General Halleck in charge of overall army headquarters in Washington. In 12/62 Burnside prepared to cross the Rapahannock River and attack Lee's forces at Fredericksburg, Virginia. He planned to cross on pontoon bridges, but Halleck managed to delay their arrival, and Burnside was afraid to send part of his forces across to establish a bridgehead, even though they would have been covered by his artillery. As a result, his engineers came under harassing fire when the pontoons arrived. Nevertheless, he got his troops over the river, some 120,000 of them to Lee's 78,000, who waited out of artillery range, dug in at the base and on the crest of Marye's Heights. Burnside's excellent plan was to hold the center and guard his bridges with a reserve and send his main force around to his left to attack Lee's right flank...but then, unaccountably, he abandoned the plan, sending only a small and inadequate flanking force and launching his main force against Lee's center, with predictable and tragic results. His men payed the price with their lives, and, defeated, he retreated back across the river.
His successor was General "Fighting Joe" Hooker, who had some 134,000 men to Lee's 60,000, and who also started out with a good plan (you can probably see where this is going). He crossed the Rapahannock with his main force upstream from Fredericksburg, near Chancellorsville in an area mostly covered by scrubby second-growth woodlands known as the Wilderness, sending a smaller force to cross downstream, largely as a diversion. He had reserves north of the river keeping pace with him to guard his supply crossings. Now he could cut off Lee's supply and escape routes, but, as ignorant of speed as McClellan, he halted for the night near Chancellorsville, and Lee moved to block him. "Fighting Joe" failed to fight, ignoring an opportunity to attack, while Lee sent part of his forces under Thomas "Stonewall" Jackson past Hooker's right flank, which Hooker obligingly left open, even though he was advised of Jackson's movements. Jackson attacked, defeating only part of Hooker's forces, but Hooker withdrew to his bridgehead. Even then he could have held off any Confederate attack, and bled Lee white if that agressive general attacked it. But he retreated north of the Rapahannock.
Finally Lincoln put General Ulysses Grant, who had won victories in the West, in charge of the Army of the Potomac, and at least Grant went all out to end the war...there would be no more retreats. On 5/5 and 5/6/64 he fought his way across the Rapahannock and through the Wilderness, but at Spotsylvania, Virginia he made no effort to save lives and entrap Lee by outflanking him, but attacked head on. At the North Ana River he at least tried a flanking move; it is important to remember that even if such a movement failed, it would force Lee into a withdrawal the South could ill afford. Grant attacked head on again at Cold Harbor on 6/3/64, losing perhaps 2,000 killed and 4,000 wounded just in one hour.
At Petersburg, Virginia, Grant's men missed opportunities to take the city and cut the supplies to Richmond, and Lee fortified it. On 7/30/64 Grant's engineers exploded a huge mine under the Confederates, knocking a literal hole in their line, but then, while the drunk and cowardly officer in charge of the attackers stayed behind, his men entered the crater and milled about until the Confederates moved back above them and slaughtered them.
The entire war was like that, and the result was perhaps 750,000 Americans dead, countless others maimed for life, lasting economic damage, and lasting bitterness. And, in view of the strange and horrible events of our most recent century, it may well be that none of this was accidental.
William B Stoecker