Some web links to mattress covers...
http://30thinfantry.org/researching.shtml
...As soon as possible and practical, the body was placed in a body bag, which sometimes consisted of only a mattress cover, and buried in a shallow grave of a temporary cemetery, although carefully marked and identified...
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http://www.medalofhonor.com/RussellDunham.htm
...Dunham's bright blue eyes show the anguish when he tells the story of how he single-handedly knocked out three German machine gun nests and saved the lives of hundreds of U. S. soldiers. Sgt. Dunham was leading foot soldiers of his platoon of Co. I, 3rd Infantry Division through the German lines at Alsace-Lorraine in France. "We broke through the German lines and were behind the enemy, " Dunham said. German machine gunners opened fire on the advancing U. S. infantryman and many soldiers fell dead in the snow. "We were pinned down by the German machine guns," Dunham recalled. Dunham mustered all his courage and quickly decided to attack the German machine gunners to save his comrades. He wrapped a white mattress cover around his body to camouflage himself in the snow. He loaded his belt with hand grenades and ammunition, picked up a fast firing automatic rifle and ran up the hill to face the German machine gunners. A German rifle bullet ripped into his back, spun him around, and he rolled down the hill. He was bleeding from his wound but he struggled back to his feet and ran back up the hill firing the automatic rifle at the machine gun nest. The mattress cover wrapped around Dunham's body was soaked with blood, making him an easy target for German soldiers. He continued up the hill, firing his rifle and throwing hand grenades. "I got so close in the German gunner that I stared right into his eyes," said Dunham, who tossed a hand grenade and silenced the machine gun. Dunham continued to run forward in the face of a hail of bullets, knocking out two more German machine gun nests and capturing enemy soldiers. His bravery on Hill 616 is a part of the World War II history...
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http://home.earthlink.net/~iversonom/ioaVEday.html
...The flight from Frankfurt to England was a rough ride, enclosed in fog most of the way. We were not able to land at an airport in south England so we dropped through a small hole in the clouds and fog and landed near Manchester. At the railway station, we met a British Major who invited us to ride in his rail cabin with him. Somehow we ended up at a camp near Salisbury, Tidsworth where the 2nd Armored Division was encamped before the invasion. We were given a mattress cover and straw to stuff it with. That was our mattress. I can remember getting the hiccups and everytime I hiccuped the mattress made a noise. About 2AM I went over to the gym and stood on my head and counted one hundred. It worked!...
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http://books.google.com/books?id=lj6yUefc2...8uVTL1ureJrlXqo
Page 30 will pop up on your screen
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http://members.home.nl/alasoe/Temporary%20...N.%20Europe.htm
See WWII Burials on that page
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http://www.pr.com/press-release/32861
...Here are the realities of that war: opening the casualty blanket rolls, seeing the dead being buried in mattress covers, the sounds, the smells and the fears of men in infantry combat. A glimpse, too, of the boys who fought the battles of World War II as they grew up or matured during the Great Depression, the rigors of infantry basic training, life in England in the weeks leading up to D-Day...
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http://www.gallagher.com/ww2/chapter12.html
...On top of the bad news about the setback in the war, we were getting off to a bad start at this new camp. It created an immediate dislike for the place that would only get worse as time went on. The first thing that happened was we were each given a mattress cover. Next, we stood in a long line leading up to a pile of straw. They shoveled the straw into the cover with a pitchfork; that was to be our mattress while we were in camp. Straw mattresses - how primitive, even for an Army camp! Grimes commented, "I thought this stuff was only used to mix with horse manure." I had not heard so much griping from my fellow GIs since the first time we arrived at Camp Irwin on the Mojave Desert during our stateside training...
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http://www.pjstar.com/stories/090907/TRI_BE6NA98S.022.php
...During a trip to the commissary for groceries, Perry and her family saw bodies of military casualties stacked inside mattress covers...
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Well that should give some idea of real life situations during the war.