“Where did the general keep his armies?”/“In his sleevies.”

A general’s “armies” usually doesn’t refer to his physical arms, but there’s a riddle:
 
Q: Where did the general keep his armies?
A: In his sleevies.
 
The joke has been cited in print since at least 1977 and has been printed on many images.
 
       
17 July 1977, The Sun-Herald (Sydney, Australia), pg. 99, col. 5:
RIDDLES
Q. Where does a general keep his armies?
A. Up his sleevies.
—Kim Masters (12), Berala.
 
Google Books
The Crack-a-Joke Book
Harmondsworth, UK: Penguin Books
1978
Pg. 37:
Where did Hitler keep his armies?
Up his sleevies.
     
Google Books
Lily, Where’s Your Daddy?
BY Nancy Weber
Richard Marek
1980
Pg. 170:
“Where did Napoleon keep his armies?” “Up his sleevies.”
 
Google Books
November 1982, Boys’ Life, “Think & Grin,” pg. 80, col. 3:
Napoleon: Where does a general keep his armies?
Wellington: In his sleevies. — T. Oderio, Los Altos, Calif.
   
26 June 1984, Boston (MA) Herald, “The Eye” by Norma Nathan, pg. 6, col. 4:
IN GENERAL: And then there’s Henry Tragert, a General Electric exec from Middleton, who is asking this question of military significance: “What do general do with their armies?” Answer: “Put them in their sleevies.” Now, that’s disarming.
   
Google Books
Sleeves:
A Treasury of Ideas, Techniques, and Patterns
By Louise Todd Cope
Penland, NC (Box 1, Penland 28765): Coat of Arms Press
1988
Pg. 2:
I offer the following riddle to those who perceive of “arms” as only power:
 
QUESTION: Where did the General hide his armies?
ANSWER: Up his sleevies!
 
24 December 1989, Seattle (WA) Times, “Traditional Siege” by Joseph Winkelman, pg. G7:
“Tell us, darling, where did Hitler keep his armies?’’
 
“Up his sleevies.”
   
New York (NY) Times
Conversations/Shari Lewis;
Lamb Chop’s Old Pal Hasn’t Changed But She Says Childhood Has
By TAMAR LEWIN
Published: December 27, 1992
(...)
“Lamb Chop’s Play-Along,” which began on public television early this year, is classic kiddie television from the long-ago era before MTV and, yes, even before Sesame Street. It’s sweet, silly and devoid of even the vaguest hint of hip. No gimmicks, just Ms. Lewis, three kids and the puppets romping through a half-hour of songs, dances, activities, skits and jokes. (Ms. Lewis’ current favorite: Q. Where do generals keep their armies? A. In their sleevies.)
   
Google Books
Napoleon and Europe
By Philip Ingram
Cheltenham, UK: Stanley Thornes
1998
Pg. ?:
While writing this book, I pulled a Christmas cracker. The joke inside read, ‘Where did Napoleon keep his armies?’ Answer: ‘Up his sleevies!’
 
Twitter
Ginger Lewman‏
@GingerLewman
Q: Where does the general keep his armies?
A: In his sleevies!
2:44 PM - 23 Nov 2007
     
Google Books
Ultimate Book of Jokes:
The Essential Collection of More Than 1,500 Jokes
By Scott McNeely
San Francisco, CA: Chronicle Books
2011
Pg. 328:
Q: Where did the general keep his armies?
A: Up his sleevies.
 
Reddit—Jokes
Where does the General keep his armies?
submitted April 2, 2013 by The_Master_of_LOLZ
Up his sleevies!
   
Google Books
Jacky Ha-Ha:
My Life Is a Joke
By James Patterson and Chris Grabenstein
New York, NY: Little, Brown
2017
Pg. ?:
We’ve all heard Jeff recite Laffy Taffy jokes before. He swears the crinkly wrappers are the best joke book ever written.
 
“Where does the general put his armies?” he asks.
 
“I don’t know,” says Victoria.
 
“In his sleevies.”
 
Reddit—Dad Jokes
Where did the general keep his armies? (self.dadjokes)
submitted January 17, 2018 by Hitchchicken
In his sleevies.