What wars and battles from throughout history would have been considered important lessons for an up-and-coming military commander in the 18th century?
“Read over and over again the campaigns of Alexander, Hannibal, Caesar, Gustavus, Turenne, Eugene and Frederic. … This is the only way to become a great general and master the secrets of the art of war. …”
Napoleon studied great men and their campaigns, not certain battles. One could say he studied the battles and wars of those men though. In his series of lectures and books comprising the Great Captain series, historian Theodore Dodge draws comparisons between the bulk of Napoleon's strategies and tactics and all of the generals quoted in Napoleon's maxims of war. Chandler also comes to similar comparisons when analyzing his tactics in Campaigns of Napoleon.
Source:
Napoleon: a history of the Art of War, Vol 1 & 2 by Theodore Dodge.
The Campaigns of Napoleon by David G. Chandler.