What were the principal events of the American Civil War?

 More Americans died in the Civil War (1861-1865) than any other conflict involving the United States. The number is estimated to be somewhere between 665,000 to 750,000 or  2% of the population. This would forever alter the landscape of American history impacting the nation’s political development even in the modern era.

The Confederate States were already identified in the previous answer (numbering 11 altogether). The Union was considerably larger and consisted of California, Connecticut, Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont and Wisconsin. 

However divisions were not always that clear with many volunteers in Tennessee choosing to fight for the Union for example. Nevada and West Virginia (who broke away from Virginia proper) would later join the Union as well.Territories on the Union side also included: Colorado, Dakota, Nebraska, New Mexico, Utah and Washington

Initially the South took advantage of their superior military leadership and more defined organizational skills by securing victories. The First Battle of Bull Run (Manassas) was such a success. Although the Eastern theatre provided much of the fighting the war had a Western, Trans-Mississippi, Pacific and Lower Seaboard side to it as well. The battle of Hampton Roads (1862) that featured the ironclad battleships the Monitor and  Virginia was once such a sea battle. It was inconclusive in the end.

Phase One of the War saw the Confederates push the offensive with several victories as Lincoln reorganized his staff to select the most suitable candidates for the Union campaign. An early Union victory took place at Fort Donelson in 1862. This was followed up by a win at Shiloh where more Americans fell in battle  than in all previous wars combined.

However the South was not to be undone and they soon fought back with Robert R,Lee blocking the Union advance on the Southern capital of Richmond, Virginia. On September 17th, 1862 the bloodiest single day battle was fought at Antietam, which while technically a Union victory was not exploited in the immediate  aftermath by the North. However it was after Antietam that Libcoln issued the famous Emancipation Proclamation freeing all slaves across both sides.

 The South would hit back with a strong win at Fredericksburg in December of the year.but the Union were given a morale injection  with a strong showing at Stones River soon afterward. The Union though were not going to have it their own way as Lee Scored his most impressive victory at Chancellorsville in July 1863. Although it did come at the expense of the life of General Stonewall Jackson the victor at First Bull Run.

At the siege of Vicksburg, Union General Ulysses defeated the Confederate, essentially cutting the enemy's lines into two. This set the stage for the Battle of Gettysburg, the largest battle of the war. Fought between the 1st and 3rd of July 1863 Gettysburg ended the Confederate thrust northward permanently., However it came at the cost of 51,112 lives.  On November 19th, 1863 Abraham Lincoln would deliver the Gettysburg Address at a National Cemetery in Pennsylvania honouring the war dead, In it he reframed the war as a fight to preserve the Union and provide ‘a government for the people by the people.’The address placed strong emphasis on the 1776 Declaration of Independence.

The post-Gettysburg period was frustrating for the Union. They were defeated at Chickamauga in Georgia, had success at Chattanooga (opening the deep South) but came up against Confederate resistance at Wilderness, Spotsylvania Court House and Wilderness, The War was appearing to settle into one of attrition as Lincoln faced a re-election vote in 1864. The common belief was that the Confederacy was hoping to cut a deal with what could be a John Frémont  presidency. 

Fortunately for Abe he had one ace up his sleeve - whose momentum building drive to the sea captured Atlanta in August 1864 virtually ensuring Lincoln of a Presidential victory. It was Sherman’s scorched earth policy that laid waste to the South that would break Confederate opposition. The Union’s manpower and industrial advantage was dominating the outcome. The South was outnumbered two to one in manpower and had a knife slash though its home front.

In April 1865 Confederate supplies were exhausted at Petersburg and on April the 9th of that same year Robert E. Lee surrendered to Grant at the Appomattox Court House, The war was over. 

The number of Union dead has been estimated at  364,000.  260,000. Confederates lost their lives, About a third of those dead were as a result of being killed in action, The rest succumbed to disease. African Americans made up 1% of the northern population but supplied 10% of the Union's troops. About 3500 Native Americans fought in the war. 

It is worth noting that the war itself was not always popular in the North. There were draft riots in New York in particular and the difficulties of fighting the costly war forced the Government to issue notes known as Greenbacks.

Important Union generals included Key Union Generals: Ulysses S. Grant, William T. Sherman, George Meade, Winfield Scott, Joseph Hooker, George McClellan, John Pope, William Rosecrans and Ambrose Burnside (known for his side burns).

The most prominent Confederate generals were Key Generals of the Confederacy: Robert E.Lee, Stonewall Jackson, Braxton Bragg. James Longstreet, George Pickett, John Hood, John Pemberton and Pierre Beauregard.

Many of these generals knew each other on both sides from time spent at military academies such as West Point and Virginia.