Green’s Dictionary of Slang

(US) canned corned beef.

1902		N.Y. Tribune 2 Nov. 37/2: Corn beef comes in for several names: out of cans it is simply ‘salt horse,’ when in cans it is ’corned willie’ and when in hash it is ‘rope yam’.
1908		Big Sandy News (Louisa, KY) 10 July 6/1: [We] were fed on corned beef (tough willie), beans, tomatoes hard tack and coffee.
1917		L.A. Times 22 Apr. III 22: Nearly every one, even those not connected with the army, knows that ‘corned Willie’ is canned corned beef. The returned guardsmen hope they may never see it again.
1918		R. Dwight diary Sept. 🌐 We lived on our Corned Bill and hard tack along with what blackberries we could for three days.
1918		Sun (NY) 22 Dec. 56/2: ’Twill make a pretty story [...] to tell the wife, Corn Willie on for breakfast, Corn Willie suppers, too.
1920		T.H. Kelly What Outfit, Buddy? 13: His emergency rations of ‘corned willy’. [Ibid.] 77: We monjayed ‘corn willy,’ black coffee, and hardtack seventeen days straight.
1944		P. Kendall Dict. Service Sl. n.p.: corn willie . . . corned beef in tins.
1949		G. McMillan Old Breed 235: Dinner was corned willie cakes.