2018 marks the 100th anniversary of the end of World War I. This four year war claimed over 8.5 million lives and wounded over 21 million. On November 11, 1918 an armistice was reached ending the war.
What were your ancestors doing during the Great War? Even if your family did not count soldiers in its ranks, those left behind on the home front were also impacted. This anniversary year is a good time to document your family’s World War I story. The links below can help your write that narrative.
Internet Archive search on the “Great War” 
Internet Archive has so many great resources from texts, to microfilm, to movies. Searching on the keywords “Great War” can help point the way to histories, poems, and personal accounts. It's important to keep in mind when searching for period accounts of World War I to not search by the keywords “World War I.” This designation would not be used until 1939 when World War II was underway.
Two Thousand Questions and Answers About the War
This book whose full title is Two Thousand Questions and Answers About the War: A Catechism of the Methods of Fighting, Travelling and Living; of the Armies, Navies and Air Fleets; of the Personalities, Politics and Geography of the Warring Countries. With seventeen new War Maps and a Pronouncing Dictionary of Names by the Review of Reviews is fully digitized on Internet Archive. Full color maps will be welcomed by family historians looking to learn more about the sites important to the war including a United States map marked with the locations of military training camps and schools. Written for Americans, the majority of the book is a Q & A about aspects of both the battle front and the home front and the countries involved. This is a must for learning more about the war and what your ancestor’s experience might have been.
National WWI Museum
When I think of the best museums I’ve had the pleasure to visit, the National World War I Museum in Kansas City, Missouri is at the top of that list. The exhibits I saw on my visit provided a real example of what life was like during the Great War. The Museum has a research library as well as a digital collection that you may search or browse from their website. “The National World War I Museum and Memorial's online collections database allows you to search digital records of our global collection that began in 1920.” The images in this online collection are just a small part of the Museum’s overall collections. A search for my great-grandfather’s navy ship, the USS New Mexico, produced only one image of the ship but a visit to the library would produce more information. Randomly browsing images will provide you an idea of the diversity of this image collection, even uncovering a photograph of identified American POWs .
It should also be mentioned that other World War I museums exist worldwide. One hyperlinked list of such museums can be found on Wikipedia.
American Ancestors World War I & World War II U.S. Veteran Research
This list of links compiled by David Allen Lambert of the New England Historic Genealogical Society provides resources including how-to guides, draft records, service records and websites. This is a good reference for starting your research for your American World War I (or World War II soldier).
This US National Archives web page on World War I gets you started researching your US soldier and includes information about service records, draft registration cards, deaths, and veterans homes. There's also a few links about African Americans in World War I. Service records for World War I will have to be ordered but draft registration cards are available online through a variety of genealogy websites. Because the United States didn't enter the war until 1917, some American men went to Canada and joined the military there. If your family member joined the Canadian military, make sure to check out the Library and Archives Personnel Records of the First World War database.
Researching your family during the First World War is much more than accessing military records. Finding images including maps, learning about life on the home front, and the history behind the war can help you tell the story of your family during this time. Other topics that could be woven in include the Influenza Pandemic, the women’s suffrage movement, and the aftermath of the war.
 “PBS: The Great War,” University of Wisconsin Oshkosh (https://www.uwosh.edu/faculty_staff/henson/188/WWI_Casualties%20and%20Deaths%20%20PBS.html: accessed 14 May 2018).