When we watch things like Stargate, there's the assumption or public perception that the military takes jurisdiction over such discoveries and handles first contact... even before hostilities have begun (after they've begun, there's no question).
I guess, part of the problem is that there are few to no unexplored things which might constitute an "expedition", however, let me expand it to include archeological discovery and the like. Are there modern real-world examples of the military injecting themselves between a scientific goal or discovery and the scientists or explorers or archeologists? Cases where the military actually leads the charge and controls the program?
If the military has taken over something, is that abnormal enough to indicate something of significance or is it something routine throughout history?
At least in the American experience, the U.S. Army and the Office of Coast Survey were among the pre-eminent scientific and exploratory agencies in the pre-Civil War era and to some extent afterward. The U.S. Army was valued because in many cases, its forts were the only significant governmental presence in a wide expanse. Thus, they served as bases for exploration and research in the surrounding area.
Furthermore, the Army's transportation surveys ─ the Army was particularly interested in logistic routes ─ were used for commercial purposes. The Army also contributed to the first regularlized system of weather measurements and weather forecasting, as doctors across the American West noted conditions for later comparison.
But if you're thinking of specific expeditions, let me refer you to the Allen Expedition of 1885. This expedition, led by Lt. Henry T. Allen, has been called "Alaska's Lewis and Clark Expedition" for good reason.
In 20 weeks, Allen's crew covered 1,500 miles of unexplored territory. They noted local conditions, created a rough map of the territory, and interviewed the inhabitants. Two years after the expedition, Allen compiled his 172-page report on the expedition, and it remains today a valuable documentation of conditions in Interior Alaska at the time. Allen included observations on animals, geology, volcanic activity, glaciers, minerals, the weather, and the people. Allen even speculated about the prehistoric links of various people he met along the way.
Sure! The Enclave's attempt to secure Project Purity in 2278 under the orders of 63rd President of the United States, John Henry Eden, was seen by a number of scholars at the time of somewhat unneccessary military interference into an entirely civil project. The facility was greatly valued at the time, since it was believed that the project's success would eventually lead to a clean scrubbing of the entire Potomac River and a rebirth of the population living around the area. The Enclave's official stance was that they were attempting to seize the facility to protect it from the ravages of raiders, super mutants and the terrorist organization known as the Brotherhood of Steel. Some fringe scholars claim, among other fantastic things, that President Eden was an AI program, that the Enclave was actually attempting to commit genocide on all capital wastelanders using a genetically modified virus... silly stuff. But actual scholars of the historiography of the period generally stick to the more sensible theories, of course.
None of this would matter in the end, as the Super-Mirelurk Revolt of 2355 would destroy nearly all records of what actually happened there. It would turn out that the purified water of the Potomac River would lay the seeds for the first of the new, sentient super-Mirelurks to evolve. The Super-Mirelurks that first rose from the purified depths of the Potomac would be the first of a new race of our Mirelurk Overlords to establish the first foothold of our vast empire.
Long live the Enclave-Thur'gur'lak alliance!