Almost none of the new Generals had any training at high levels.
Many were Colonels left over from the Mexican War, fifteen years earlier - a dubious qualification, as the Confederates found when they made Jefferson Davis President.
The challenge was to choose and use largely untrained officers. Lincoln proved better than Davis at this.
This is a matter of opinion, but the South probably had the better generals at the start of the Civil War.
Grant and Sherman
The major and most prominent generals in the US Civil War can be narrowed down to two generals. For the South the prominent general was Robert E. Lee. For the North it would be US Grant.
The most important Civil War generals were General Ulysses S. Grant for the North and General Robert E. Lee for the South.
Grant for the North, Lee for the South
Lee for the South and Grant for the North were the most famous.
Well that's really a matter of opinion. For the North Sherman and Grant were both good generals- but Lee is probably commonly considered to be the best general of the war.
The South - Robert E. Lee / North - Ulysses S. Grant .
The easiest anwser is that the North had technology, shear number of troops, and industry on their side. The South had much better generals, a more willingness to fight, and that the war was fought in their back yard
In three words: Northern military incompetence. The Union had a few good generals, Grant most notably, but most of the Union generals were outclassed by the Confederate generals. The North held every advantage in this war except for a surplus of competent generals.
Civil War Generals II was created in 1997.
Civil War Generals II happened in 1997.