Each spring, a group of military payment certificate (MPC) collectors and experts in military numismatics gather in Port Clinton, Ohio, for MPC Fest.  I've been invited for several years now but with family obligations I've not yet been able to attend.  Hoping to next year for their 20th Fest.This year, the MPC Fest group decided to do a post-Fest tour of military museums in the region.  This was an opportunity for those Festers that had traveled from quite a ways to make double-duty of their travel budgets and take advantage of being here to see some really great museums of military history... some of which, of course, include items of numismatic interest.  One of the best military museums in the world is the National Museum of the United States Air Force, located at Wright Patterson Air Force Base, Ohio.  When my son and I found out the MPC Festers were planning to visit it, we thought, well, since we can't make the Fest this weekend, maybe we can meet up with some of them at the NMUSAF instead.  So we did.We met with several Festers and a spouse or two that made the trek to the Museum.  We already knew Fred Schwan from meeting him at the huge annual D-Day reenactment in Conneaut, Ohio (www.ddayohio.us), but we had not yet met Joe Boling.  Fred and Joe co-wrote the book "World War II Remembered:  History In Your Hands, A Numismatic Study" (https://www.amazon.com/World-War-II-Remembered-Numismatic/dp/0931960401).  We were glad to meet Joe and his wife, along with Bill, Mike, Dave, and Brett (who is involved with the Central States Numismatic Society).  We toured around looking at all the amazing aircraft and historic exhibits, which included a couple of notable numismatic items in the WW2 hangar:  a long example of a "short snorter" (the type with banknotes from various countries taped together end-to-end), and a display regarding a rather infamous example of another type of short snorter, the type where one would gather signatures of many people on a single note.  I say infamous because typically the signatures gathered would be of friends, military unit-mates, or famous figures and celebrities whenever they were encountered.  This note had signatures of 25 high-ranking individuals, but not any who the typical US GI would have considered friends.  They were the leaders of the Japanese war machine, and the signatures were collected on a post-war 100 yen note by an American guard at the Sugamo Prison, where the accused were being held during their trials for war crimes.  Included on the note was the signature of Hideki Tojo, probably the most recognizable Japanese name to the American public at the time aside from Emperor Hirohito.  (Hirohito was not put on trial, per an agreement between the Allies and Japan as part of their surrender.)  Of those who signed the banknote, a handful ended up being executed (including Tojo), but most served prison terms before being released.Military history and numismatics overlap in many ways.  Wars not only cost a country a lot of money to wage, they also have effects on the forms of currency themselves.  Coin collectors will encounter these effects sooner or later; whether they realize the connections or not is a matter of how much history the collector knows.  Even if history isn't one of your main interests, a knowledge of it helps you understand the changes in coinage and currency that you see as you sort through and collect these items.  The disappearance of metals like silver, copper, and nickel from coins and their replacement with metals like zinc, steel, tin, or even ceramic or fibrous materials is often an indication of the toll of wartime material shortages.  The changes in national symbols on coins and paper money from certain areas can be indicators of a change in governments effected by war, as nations are conquered and occupied, and then later liberated.  This only touches on national currency used by civilian populations.  There is an entire subset of numismatics dealing with coins, currency, and other financial items made for the exclusive use of military personnel from various nations:  Allied Military Currency (AMC), Military Payment Certificates (MPC), military currency or "canteen money", transfer currency to be used to transfer between war zones, etc...  even banknotes included in escape kits for fliers shot down over foreign territories.  Wars have affected most American families in that most people had a family member involved in one in some way or another.  I had a brother in the Vietnam War, four uncles in WW2, a grandfather in WW1, a direct ancestor in the French and Indian War, and many more relatives in the military from the American Revolution through the Civil War to modern times.  Making the connection between wartime numismatics and family history just makes the hobby all that more interesting... at least to my son and me.  This is what makes this subset of numismatics so fascinating to many people.The NMUSAF is always a fun place to visit, but this trip we were most happy to be able to talk with these experts and make some new friends.