Canada War Tax Stamp, One Cent

 Canada (probably due to its' size and the large quantity of WarTax stamps needed) was the only country that had "War Tax" as part of the stamps design; all other nations (most of which where smaller islands in the British Commonwealth simply resorted to overprinting existing issues, which was less expensive than having new designs created.

I myself have exhibited WarTax stamps on cover (buying the mint stamps is easy and cheap, finding them used on covers or postcards is not...); see my WarTax page at http://wartaxstamps.webs.com

The proceeds of the WarTax were primarily to help defray expenses incurred due to the war; some of the Caribbean islands used it to help pay for the expenses of their "contingents" (ie: the troops that they provided), Bermuda for the loss of their tourist trade when the USA entered the war, Turks & Caicos for loss of revenue due to a reduction in the export of crops, etc (info taken from John Davis' "War Tax Stamps of the British Empire First World War).

 Dominica War Tax Stamp, Half Penny