From 'Plain and Fancy Needlework', November 1917, this pattern shows how to crochet Knee Caps. They only take one half hank Germantown knitting yarn, and a No. 3 1/2 hook. And I'm sure the soldier boys will appreciate them!
Chain 41, double crochet, always taking the back loop; 8 rows even.
9th Row - 17 stitches, 2 stitches in next stitch, 4 stitches, 2 in next stitch, 17 stitches.
10th Row - No increasing.
Repeat 9th and 10th rows until there are 27 rows. Then work 12 rows without increasing.
Then decrease in the way you increased until work matches first half. Sew up with yarn.
"If you have no one in particular to give them to, send them to the National Surgical Dressings Committee of America, 845 First National Bank Building, Chicago, Ill."