The class of 1814 had 4 of its graduates fight in the civil war 1 for the confederates and 3 for the union, 1815 2 confederates and 3 unionists, 1817 2 confederates and 2 unionists, 1820 1 confederate 3 unionists, 1822 2 confederates 10 unionists, 1823 1 confederate 8 unionists, 1825 3 confederates 7 unionists, 1826 5 confederates 8 unionists, 1827 3 confederates 7 unionists, 1828 4 confederates 3 unionists, 1829 4 confederates 15 unionists, 1830 6 confederates 6 unionists, 1831 3 confederates 9 unionists, 1832 6 confederates 9 unionists, 1833 5 confederates 12 unionists, 1834 5 confederates 12 unionists, 1835 7 confederates 18 unionists, 1836 4 confederates 12 unionists, 1837 10 confederates 11 unionists, 1838 10 confederates 11 unionists, 1839 4 confederates 14 unionists, 1840 10 confederates 15 unionists, 1841 12 confederates 22 unionists, 1842 13 confederates 21 unionists, 1843 4 confederates 17 unionists, 1844 3 confederates 5 unionists, 1845 7 confederates 15 unionists, 1846 11 confederates 26 unionists, 1847 4 confederates 27 unionists, 1848 10 confederates 15 unionists, 1849 13 confederates 24 unionists, 1850 18 confederates 19 unionists, 1851 8 confederates 30 unionists, 1852 12 confederates 24 unionists, 1853 13 confederates 34 unionists, 1854 14 confederates 22 unionists, 1855 7 confederates 24 unionists, 1856 10 confederates 34 unionists, 1857 14 confederates 21 unionists and 2 who switched sides, 1858 11 confederates 14 unionists, 1859 5 confederates 17 unionists, 1860 9 confederates 32 unionists, May 1861 8 confederates 37 unionists and June 1861 4 confederates 30 unionists.
These are all the classes that had graduates on both sides of the war, what was going through their minds to learn that the same men who they had once shared a class with were now their enemies, did any face off against each other in battle, and did any of those who survived the war reconcile afterwards?
Source
https://civilwarintheeast.com/west-point-officers-in-the-civil-war/
Yes they knew this was happening. Yes they faced off in battle. And yes there was reconciliation afterwards. I will focus on one strange post-war wrinkle of history.
Clearly you are interested in the Civil War. After the war (like most wars) there is tremendous dislocation, rich families on the losing side become poor, men become mercenaries or soldiers of fortune, etc.
During 1874-1878, Egypt (as part of the Ottoman Empire) fought a colonial war with Ethiopia. Roughly speaking, the Ottomans wanted to control all of Africa north of the equator (including pushing Egypt's borders down across Sudan, and east to include Suez and Somali). Ethiopia was an ancient Christian territory, and the Islamic Ottoman-Egyptians wanted to conquer it.
Egypt was wealthy, but Ethiopia had more people. So what do you do? You hire mercenaries to train your army. To bolster their military, the Egyptians hired ex-Civil War officers to reorganize, train, and lead their military in this war between Egypt an Ethiopia. Starting in 1870, former Confederate officers began working for the Ottomans as military advisers. Thaddeus P. Mott, a Union officer, was involved in recruiting officers from both sides for service in Egypt. These Confederate officers moved 6,000 miles around the world to lead Islamic North African soldiers into war in the Ethiopia highlands. The first Confederates there (Henry Hopkins Sibley (West Point, then Confederate General) and William Wing Loring (Confederate General)) were at the recommendation of their former arch-nemesis, General Sherman**.** General Charles Pomery Stone (West Point, then Union) was also recruited by Mott.
These guys (Mott, Loring, Sibley, and Stone) recruited a host of former Union and Confederate officers (many from West Point or the Naval Academy) to also move to Egypt and work together to reorganize, oversee construction of coastal fortifications and batteries, teach modern infantry and artillery tactics, and lead the Egyptian army in a war in Ethiopia.
So in the fallout of the American Civil War you have former foes, working together, leading Muslim-Arabs in a war against Christian-Africans. This is stranger than a Hollywood movie.
There is one memoir of the war, written by Loring.
https://archive.org/details/aconfederatesol00lorigoog/page/n10
Similarly, you have Dr. Edward Warren, who was from prominent Virginia families on both maternal and paternal sides, went to boarding school, went to UVA, went to medical school, and then studied medicine in Paris. During the Civil War he holds various high medical positions both in the Confederate army and then as Surgeon General of North Carolina. He writes and publishes a field manual for for military surgery.
He bounces around after the war trying to put rebuild/reopen various Southern medical schools, and then goes to Egypt in 1875 to become Chief Surgeon, removing a tumor and repairing a hernia on the Egyptian minister of war. After basically saving the life of a high ranking Egyptian official, he is given an aristocratic title and begins to run in high circles in Egypt. He then runs into a number of other ex-Confederates who have been hired by Egypt and move in these elite circles. He publishes a 600 page collection of his letters and essays and life history, "A Doctor's Experience in Three Continents."
Ultimately, Egypt sort of lost the Egyptian-Ethiopian War (the two main battles were sort of a loss or a draw). Egypt had the most money, the better equipment, and private military advisors from the Union and Confederacy working together, but it had to operate with long extended supply lines in hostile territory. It's relations with Ethiopia remained in constant tension.
The Ethiopians had a British military advisor helping them, John Kirkham. He originally ended up there as part of the British Expedition to Abyssinia. However he stayed and took up the side of the Ethiopians. He was captured by the Egyptians and held in a lion's cage for about six months with basically no food but given lots of alcohol. Eventually some British sailors happen upon him and want to free him, but are told that Kirkham foresake his British citizenship and passport when he joined the side of the Ethiopians. He died about six months later from dysentery and alcohol poisoning. General Loring writes about seeing Kirkham in his memoir.