A sobering bit of history:<p>

I have just added the "B A B" TRENCH CODE No. 4. to my
collection. Probably published in May 1917 and issued to a
Maj. Hathaway 2nd Bn. this is one of the British trench
codes of World War I.<p>

Trench codes were employed during World War I for rapid
communications of tactical situations at the front and
consisted of 3 letter or 3 digit codes.<p>

Trench codes were obsoleted at a rapid pace due to the
relative ease in reconstructing the code or loss or
capture. Thus, new versions of the code were regularly
pressed into service and old copies destroyed.<p>

I suspect that this little 41 page booklet survived either
because it never made it to the front or Major Hathaway
only served at the front for a brief time.  Pages 12 and
13 relating to Gas and Bombing Attacks are still uncut and
the booklet was obviously never opened to these pages.<p>

Here are a few of the codes and their corresponding
phrases:<p>

017 Asphyxiating shells<br>
025 Lachrymatory shells<br>
117 Creeping barrage<br>
139 Our artillery is shelling us<br>
185 Minenwerfers<br>
186 Flammenwerfers<br>
237 Gas<br>
367 Tank approaching ...<br>
390 ... will sweep "no man's land" in front of ...
subsector between (hours)<br>
730 I have not got the code