Just as technology has changed the nature of warfare in Iraq, it has added a new dimension to the way soldiers at the front communicate with loved ones back home.
E-mail, which was barely known during the Persian Gulf War 12 years ago, has enabled soldiers, sailors and Marines to stay in touch with family and friends as if they were in a downtown office instead of a war zone.
By enabling communication in real time, e-mail allows both sides to keep up with the minutiae of daily life, offering a special sense of closeness.
For thousands of correspondents at home, it has brought immediate relief, as each new electronic message confirms that -- for one specific moment -- a loved one is safe and out of harm's way.
Yet for all its benefits, e-mail can sometimes seem a poor substitute for a letter.
"You can print e-mail out, but there's a coldness to it," said Nancy Pope, a historian for the National Postal Museum in Washington, D.C. "It looks like a memo from your boss. Pound for pound, there's more emotional power in letters than in e-mail."
Letters take time to write, so they naturally lend themselves to introspection and thoughtful language. As physical objects, they offer a tangible connection between the writer and recipient. And because letters are written less frequently than e-mails, there is the persistent knowledge that the words a soldier commits to paper may be the last ones read by loved ones at home.
"Letters are the one connection that remains between the front line and the home front," said Andrew Carroll, author of "War Letters: Extraordinary Correspondence From American Wars." "Where there's an actual piece of paper going back and forth, there's a tangible connection."
War letters have always changed to reflect the times in which they were written. Few people understand this as well as members of the Cooley family, a clan that has produced nine generations of soldiers who have served in seven American wars.
During the Revolutionary War, berry juice often was used in place of ink, and cloth stood in for paper when it was in short supply. The rebels, including John Alden Cooley, had to rely on lone postal riders to smuggle mail between camps of the Continental Army. Many women weren't literate, so each letter had to be read aloud by a male relative or family friend. All these factors combined to make letters home a rare thing.
By the time of the Civil War, an independent postal service was emerging and writing had become more common.
Gilbert Cooley, a farmer from Strawberry Point, Iowa, became a captain in Iowa's Regular Infantry. Notes to his wife, Martha, focused on life back home.
The letters would take months to arrive, delaying the pacing of the conversation between husband and wife.
As money became increasingly tight, Martha wrote about her struggles to keep the farm running. After reading about an offer to buy some of the land, Gilbert penned a simple warning.
Don't sell the farm.
By the time Martha received the letter, 40 acres already had been sold.
During World War II, Navy aerial photographer Theodore "R" Cooley spent months flying above the sea battles in the Pacific Ocean, documenting the movements of the Japanese fleet. The family was impatient for updates but also happy to wait for a handwritten letter.
"If you got the news quickly, particularly during World War I and II, it meant you were getting a telegram," said Carla Kaplan, an English professor at USC who specializes in correspondence. "Fast news usually meant bad news, and that someone had died."
But technology was already beginning to depersonalize the connection between writer and reader. Eager to free up shipping space for wartime materiel, the military introduced "V-Mail."
After the one-page letterforms were filled out, they were photographed onto microfiche. Then the film was shipped to a central base overseas, where each letter was printed out and distributed as a photograph. Soldiers could read the notes and see their loved ones' handwriting, but they were merely copies of the real things.
During the Vietnam War, GIs dictated long messages into portable tape recorders.
Such personal cues frequently are absent in e-mail, which the military began using around the time Army Capt. Tobalina Cooley Beck was sent to Somalia in 1991.
The Prodigy online service was running a trial program called USA Connect, allowing participants to write brief notes to soldiers in the east African nation. Prodigy then forwarded the e-mails to a central military computer server in Mogadishu, where they where printed out, folded into envelopes and distributed.
Her husband, Steve Beck, signed up for the service and often typed sentences that were to the point, like in a telegram.
Everything is fine. The weather is nice. We miss you and love you.