I would characterize the Mexican Expedition as a learning experience for the American military, both for the soldiers actually in it, and the branches of the military themselves. I also would say that it is America's first man hunt into another country, searching for Pancho Villa after killing several US citizens in Columbus, New Mexico as a sign of retaliation for the US backing another person for the Mexican presidency. Furthermore it was not one of the most effective small wars, because the mission was to retrieve Pancho Villa and bring him back to the US dead or alive, neither of which were carried out because he was never found. .
The Mexican Expedition was a learning experience for the American military and those involved in it for a number of reasons. Some being that tactics were tried out for the first time, and some being that the soldiers who would go on to become great military commanders would see their first taste of leading battle in this war. Also, America had to proceed with caution because they were going into another sovereign country to find one person, this had to be a light footed expedition as to not stir up any more trouble than they already had their hands full with. For the first time in American military history, the US flew it's first air combat missions to scout the land below for signs of Villa's men and possibly his whereabouts. There were a total of eight planes that took place in these scouting missions, leading the way for further use of airplanes in wars to come for the US. As for learning experiences of great military commanders, the at the time Lieutenant George S Patton was in Mexico during this expedition and lead troops for the first time. His first combat experience was on May 14th, 1916 which is also known for the US's first motorized attack in combat history. Patton lead men in Dodge Touring cars equipped with machine guns to track down and kill Villa's men.