My roomate and I were having a discussion about Europe's opinion on the American Military after the Civil War. I believe that Europe did not think of the US as a threat or a serious World Power, and thought of our military as laughable because USA was such a young nation and just went through a civil war. On the other hand, my roomate stated that America (right after the Civil War) had the largest standing army in the world, and the European powers knew of this. Can anyone cite some sources proving either one of us correct? Or if we are both wrong, show us the correct answer. Thank you!
First of all the U.S. did not have the largest standing army in the world; that much is a farce. In fact following the Civil War the U.S. went a massive demilitarization and did the same exact thing following the First World War as well. That's probably one of the biggest things about American military history early on; we did not have a large standing army; be it ideological or financial reasons it varies from historian to historian but regardless within a few years after 1865 our army size was down to about 25,000 men. Compare this to, say, the French and Germans in the Franco-Prussian War (1871) and they had 500,000 and 300,000 active regulars respectively with ~400,000 and ~900,000 reservists respectively who were pre-trained (think "weekend warriors").
You are more or less correct; the world did not take us very seriously. See this post below where I go into depth on this topic:
The U.S., in short, was busy learning lessons from the Napoleonic Wars while Europe was moving into a style of war more akin to WWI/WWII (e.g., what we associate with "modern" warfare); this is mainly because, well, the Civil War was America's first real experience with the Western style of warfare since 1783. We don't know whether or not Helmuth von Moltke the Elder (the military genius behind the rapid victory in the Franco-Prussian War!) actually referred to the American experience as "two armed mobs chasing each other around the country, from which nothing could be learned"; we just know that it's actually something that holds a lot of truth in it and really summarizes perceptions of their capacity (or lack thereof) to fight. Specifically I want to point out this quote from my post:
US Officers were also largely amateurs. While lower level officers in the South were certainly experienced to some regard with military life because of the large reliance on local militias both sides lacked experienced higher echelon officers who were experienced in staff work, field command, larger unit maneuvers and logistics. The only real experience with this was in General Scott's campaign in the Mexican-American War which had about 12,000 men total. The only real requirement for being an officer [in the American Civil War] was that you had the funds to support your men and the will to lead them or if you knew someone who was and jumped on ship.
Their officers were largely untrained and unskilled and their doctrine was, in essence, trying to copy paste what Napoleon did but without light infantry and cavalry or grand batteries. Granted they began to get themselves together by 1864 but that's three years of suffering on the job experience of getting their butts handed to each other. I really recommend reading through my post thoroughly as it goes over the major points pretty well.
A fantastic source on this is With a Sword in One Hand and Jomini in the Other: The Problem of Military Thought in the Civil War North by Carol Reardon. It's short but it tackles these issues well.