Igor Markov's answer to Why does the US government spend so much on military? Jon Davis' answer to Given that China is fine without blue-water navy, why does the US need one? Being even is the Deadliest form of Warfare
Imho the most influential war in history is the Caesar Augustus' failing attempt to conquer the Germans. He sent two legions over the Limes Renano expecting to tame the german population. It didn't happened: in the Battle of Teutoburg Forest the army of 15.000 well trained roman solders was completely slayed but Germans. In a what if...
Battle of Palo Alto. The first major conflict of the Mexican-American War, the Battle of Palo Alto (fought just north of modern-day Brownsville, Texas) ends indecisively. U.S. General Zachary Taylor loses 9 men and 43 more are wounded; over 200 Mexican soldiers are killed and over 125 wounded.