History of Creamed Chipped Beef (a.k.a. S.O.S.)?

Did anyone else out there grow up on creamed chipped beef (also known as cream dried beef and sh$t on a shingle)? I know from my WWII veteran grandfather that it was notorious army food, and I suspect that it became mainstream in WWII and Depression-era America as a cheap way to stretch out the rations...there seems to be a tie to Pennsylvania Dutch cuisine, too...but beyond that I can't seem to trace its origin. I've included a basic recipe below for anyone who hasn't yet tried it. It's one of my favorite comfort foods--dried beef cooked in a bechamel sauce and served over toasted bread or potatoes. It's not exactly a "looker," but it's super easy, cheap, and incredibly filling!

http://www.anunstilllife.com/

Total Time:  about 1 hour Active Time:  n/a Number Serves:  4 Equipment:  n/a

Ingredients:

1/2 cup unsalted butter
1/2 lb dried chipped beef (ask for it at your grocer's deli counter)
1 cup all-purpose flour
3-1/2 cups whole milk or half-and-half
Freshly ground black pepper
Fresh flat-leaf parsley, chopped

Procedures:

Melt the butter in a large nonstick saucepan.

Shred the chipped beef by hand into small pieces, and add it to the melted butter. Cook over medium-high heat just until the edges of the meat curl, about 10 minutes.

Stir in flour and mix thoroughly. Then add the milk, reduce the heat to medium-low, and stir constantly until the mixture is thick, smooth, and bubbly. (Depending on your desired consistency, this could take 20 minutes or up to 1 hour.)

When the sauce has thickened, turn up the heat and boil it, whisking constantly, for 1 minute.

Remove from heat, season to taste with black pepper, and serve over toast or baked potatoes with parsley sprinkled over top.