With the advent of autumn, we are reminded of the men and women who gave of themselves to serve in the various conflicts in our country's history. Veterans' Day and the anniversary of Pearl Harbor cause us to reflect on service people, past and present.
Researching these people can add to your family tree as well. While there are many sites on the Internet that researchers can use to find data such as histories, regimental pictures, and other information, some careful consideration can help you to focus in on what you want to find.
Most of the people you will be looking for will probably be male. Traditionally, men have made up the vast majority of people who have gone off to fight. Women traditionally have been involved in support and auxiliary units, and only rarely have gotten into combat on purpose.
If a male was between the ages of about 16 and 60, they may have been involved in a military capacity. Remember that records can exist from colonial periods as well as after the establishment of the United States as a country. Queen Anne's War, King William's War, Indian actions, and other conflicts took place before the Revolutionary War, and if you have ancestors who were here during the colonial era, they may have left records of service (including bounty land records and the like), in various locations.
The Revolutionary War, War of 1812, and other various conflicts (such as the Mexican actions) took place before the Civil War. Following that, there were more Indian actions, the Spanish American War, and the World Wars. Lastly, there are the recent conflicts in the late 20th and early 21st century. While we know that war is very unpleasant, we don't make judgments on it here—we are trying to find information.
Think of where you can look for records. The LDS library system has a very good brochure detailing sources and books that are helpful for military research. Most the state research booklets also contain a section on military records with useful notations.
When you send for records or visit an archive, always look at whatever you can find. I know of searchers who were sent partial records from a file. When they later visited the archives, they found many more pages of handwritten data which gave exact dates of immigration, marriage, relatives' names, earlier marriages and relationships, movements around the country, degrees of injury if they claimed a pension for that--and all of which were not in the original papers photocopied and sent.
Look in your local libraries as well as online. While there are some fantastic online sources, check books! When were the people inducted into the service? A recent project showed a group of college students the entries for some local persons who had died in World War I, and the look on their faces as they realized that they were probably looking at the only surviving pictures of people their age, from nearly 100 years ago was something to behold. For that matter so was the look of recent researchers when they found out that the man they thought had been killed in action in 1944 had survived, had been a POW . . . and was still alive and living only a few miles away.
Any specific era of conflict, and even the region that you are researching, will have it's own specific sources and topics that you can examine. Pamphlets may be written on general history, regimental histories may have unit descriptions and individual scrapbooks, and even obituaries of people may have a summary of their service appearing at the end of their life. Personality articles may also be published on anniversaries.
Don't just think that someone might have served—try to determine if they were the right age, were in the right area, and even received a pension or land. Examine your local (to the time and place of the person) land records, cemetery records. Get a good book on types of records, and check them off as you work through. Following are a few resources:
Church of Jesus Christ of Latter Day Saints: Research Outline, US Military Records
Knox, Deborah Johnson: World War II Military Records - A Family Historian's Guide, Independent Pub Group, 2003
Knox, Deborah Johnson: How to Locate Anyone Who Is or Has Been in the Military, Independent Pub Group, 1999.