In Canada, the Canadian Red Cross organized knitters. The following quote is from the minutes of the meeting of the Red Cross Society of Brackley Beach, Prince Edward Island in 1940:
At this time we were all accustomed to knitting – indeed did not every mitten, sock, hat and scarf come as a result of our abilities – but not all were familiar with following patterns. The Red Cross booklet "Knitting Instructions for War Work" was printed in November 1940 and after looking at the instructions for heavy service socks with shaped leg, double heel and flat toe; toque useful for a sleeping cap, or half mitts with finger sections, we realize the amount of time and skill required for each item and a beginner might well be content to produce a seaman's scarf!! Knitted and quilted into every item in hand were prayers, love and concern for the person who would eventually wear the socks or mittens. (my emphasis)The American Red Cross led the charge in the United States encouraging people to knit for the allied soldiers overseas. This is a poster from WWI.
The Khaki Knitting Book was published in New York in 1917 with the purpose of providing patterns for those who wanted to knit for the WWI war effort. It had dozens of patterns for things like Men's Trench Caps, Knitted Eye Bandages and Regulation Socks. This is an example of one of the patterns:
Also from the Khaki Knitting Book is this poem which speaks to the power of our knitting.