The 3rd day says, "Regimental censorship of letters discontinued." What types of things was the Army afraid that men would reveal in letters sent home?
Censorship of soldiers’ letters was undertaken by regimental Ofﬁcers. Its main purpose was to avoid mention of operational details that might prove of value to the enemy. Forbidden information included references to locations, numbers of troops, criticism of superiors and even the weather (which might indicate the state of the trenches).
To avoid censorship, soldiers could use a “green envelope” in which the writer would seal his letter and conﬁrm that “the contents refer to nothing but private and family matters”. While the letter was still liable to be checked, this method encouraged soldiers to write more personal communications which, invariably, contained military details that might otherwise have been suppressed.
Another option was the Field Service Postcard, a pre-printed card (pictured below) with optional text which could be deleted as appropriate to transmit basic information (“I am well, letter to follow”) in a quick and simple way. Captain Billie Nevill, who later found fame for kicking a football ahead of the advance on the ﬁrst day of the Battle of the Somme, conﬁrmed the importance of such postcards: “It’s a wonderful thing, a Field Service Postcard. It costs nothing, takes no time, and gives no mental energy. It is in fact the essence of laziness, the ideal of the wordless correspondent and the bored nephew alike. From it may spring a parcel, a letter, anything!”
by cyngast moderator
The army wanted to keep any information that could possibly be useful to the enemy from being included in soldiers' letters home. They believed there was always a chance that the letter or information could end up in enemy hands somehow. However, the army also censored information that could be damaging to morale at home, such as mention of large numbers of casualties, criticism of officers or operations, etc. Here's another link that gives some details: http://www.bbc.co.uk/guides/zqtmyrd