That's when those on the battlefront received letters, packages and other correspondence from their families on the home front.
A new traveling exhibit organized and circulated by the Smithsonian Institution Traveling Exhibition Service examines the history of America's military postal system. It shows how, even in today's era of instant communication, troops overseas continue to treasure mail delivered from home.
"Mail Call" is now on display at the Park City Museum through Sunday, Oct. 20.
The exhibit, which features audio stations, flip books and photos, was developed by the National Postal Museum in Washington, D.C., said Courtney Titus, curator of collections for the Park City Museum.
"They have the permanent exhibit and we are showing the traveling one, but they both deal with the history of military mail and communication," Titus said during an interview with The Park Record. "It's all about how those in the military receive letters and correspondence from their friends and families at home, and how important mail is for morale."
The exhibit's timeline stretches from the Revolutionary War through the modern day.
It also examines behind the scenes to show how difficult it is to get the mail where it needs to go, Titus said.
"Both the United State Postal Service and the military share in the responsibility of processing those letters and packages," she said.
Titus said what we know as free home delivery was established during the Civil War.
"This started because a postal worker named Joseph Briggs felt sorry for all the people who waited in long lines just to receive their mail," Titus explained. "In 1863, he developed a way for people to get the mail without having to come to the post office and stand in line, and after the Civil War the Postal Service gave military veterans jobs delivering the mail."
During World War I, a new military numbering system, called APO, was developed because the soldiers were called to service in various parts of the world.
"APO stands for Army Post Office and it was developed to make mail delivery easier and more accurate to process," Titus said. "And most of the current system of military mail that is used today was in place by the middle of World War II."
Letters to military personnel are delivered by the U.S. Postal Service to a processing center.
"From there, the military takes over and makes the deliveries," she said. "This process is important, because it can be very difficult to get these letters to some of the places where these people are serving."
In addition to the audio stations, flip books and photos, "Mail Call" features displays of artifacts, comprised of actual letters and reproductions of letters, a palm-fiber mat, a coconut and a bamboo pole that was used to send a painting.
"The mat, coconut, and pole are examples of souvenir mail, and people would send these unusually formed items to their friends or families," Titus said. "This display shows how they did it."
One of the exhibit's displays that struck a note with Titus is about Victory Mail, or V-Mail.
"I had heard about it, but wasn't really sure how it worked. But while we put the exhibit together, I found that V-Mail was a system of microfilm mail that was developed during World War II in 1942," she said. "It was a way to condense the amount of mail that was being sent to soldiers in to a more manageable pile."
Letter writers at home were given a V-Mail packet that included a standardized V-Mail form on to write their letters, Titus said.
The post office gave people two free V-Mail forms a day to encourage their use.
"The letters would be sent to a lab and converted to microfilm, and then sent off to recipients," Titus said. "Approximately 150,000 letters that were on the microfilm could fit into one mailbag, and if it wasn't for the microfilm, all those the letters would easily fill 37 large mailbags."
The current version of V-Mail is called Moto Mail.
"In this day of instant communication, people will send an email through a secure military system and the email is printed out and given to the soldiers so they will have a real, tangible letter they can hold and read," Titus said.
Another display that Titus likes includes a series of letters that were sent between a wife and her husband who was off fighting during the Civil War.
"There are quite a few letters, so people can see what happened with the couple as time progressed," she said. "It's all there in the letters."
In connection with the "Mail Call" exhibit, the Park City Museum is planning some special programming.
"We are offering a free locals day on Thursday, May 30, where Summit County residents can come and explore the exhibit for free," Titus said.
Then, on June 20, the museum will host a community-giving day.
"We will collect letters, supplies and sundries for care packages that will be sent to our military overseas," Titus said.
Also, throughout the exhibit, the museum is participating in The Blue Star Museums program.
The program is a partnership with Blue Star Families, the National Endowment for the Arts, the U.S. Department of Defense and more than 1,800 museums across the country, Titus said.
"We are offering free admission to all active military personnel and their families," she said. "Nationally, the program will run through Labor Day, but we're going to offer free admission through Oct. 20."
"Mail Call" will be on display at the Park City Museum, 528 Main St., through Sunday, Oct. 20. The museum is open Mondays through Saturdays from 11 a.m. until 6 p.m. and Sundays from noon until 6 p.m. Admission is $10 for adults and $8 for students, senior citizens and the military. Youths ages seven through 17 are $5 and children ages six and younger are free. For more information, visit www.parkcityhistory.org . For more information about Blue Star Families, visit http://www.nea.gov/national/bluestarmuseums .