“In victory, you deserve champagne; in defeat, you need it” has been frequently credited to Napoléon Bonaparte (1769-1821), but there’s no evidence that he ever said it. Winston Churchill (1874-1965) favored Champagne Pol Roger. Churchill wrote in 1946:
 
“I could not live without Champagne. In victory I deserve it. In defeat I need it. “
   
Churchill might have been quoting an existing saying, but citations earlier than 1946 have not been found.
     
 
Wikipedia: Champagne Pol Roger
Champagne Pol Roger (founded 1849) is a notable producer of champagne. The brand is still owned and run by the descendants of Pol Roger. Based around the town of Épernay in the Champagne region, the house annually produces around 110,000 cases of Champagne.
(...)
Champagnes
The house’s prestige label is the vintage Cuvée Sir Winston Churchill. Churchill is quoted as saying of his favourite tipple “In victory, deserve it. In defeat, need it!”.
             
Google Books
The Spectator
Volume 239, Issue 1
1977
Pg. 28:
When in doubt, champagne is the sure safe choice—‘In victory, you deserve it, in defeat you need it’—and the Jubilee wines made for 1977 certainly merit attention,
 
Google Books
French Vintage:
A Personal Selection
By Pamela Vandyke Price
London: Harrap
1986
Pg. 89:
Yet competition in the export markets for Champagne remained keen. Well, the saying ‘In victory you deserve it, in defeat you need it’ has been cited for a long time.
 
Google Books
Champagne:
The History and Character of the World’s Most Celebrated Wine
By Serena Sutcliffe
New York, NY: Simon and Schuster
1988
Pg. 21:
The Bonapartes were frequent customers — Napoleon is reputed to have said of champagne: “In victory you deserve it, in defeat you need it.”
 
Google Books
Windows on the World Complete Wine Course
By Kevin Zraly (Windows on the World, New York, NY)
New York, NY: Sterling Publishing Company
1989
Pg. 134:
“In victory you deserve it; in defeat you need it.” — Christian Pol Roger
 
Google Books
Churchill by Himself:
The Definitive Collection of Quotations
Edited by Richard Langworth
New York, NY: PublicAffairs
2008
Pg. 537:
I could not live without Champagne. In victory I deserve it. In defeat I need it.
1946, EPERNAY. CHRISTIAN POL-ROGER TO THE EDITOR.
WSC to Mme.Odette Pol-Roger in proposing a visit (unrealized) to her home, which he called “the world’s most drinkable address.”
 
Google Books
The Quotable Drunkard:
Words of Wit, Wisdom, and Philosophy From the Bottom of the Glass
By Steven Kates
Avon, MA: Adams Media
2011
Pg. 52:
“In victory, you deserve Champagne; in defeat, you need it.” —NAPOLEON BONAPARTE
 
Google Books
Oxford Dictionary of Humorous Quotations
Edited by Gyles Brandreth
Oxford: Oxford University Press
2013
Pg. 47:
In victory, you deserve champagne, in defeat, you need it.
. Anonymous: modern saying, frequently associated with Napoleon I, but without evidence
 
Google Books
How to Think Like Churchill
By Daniel Smith
London: Michael O’Mara Books Limited
2015
Pg. ?:
He (Winston Churchill—ed.) also enjoyed a little port, brandy (Hine for preference) and Pol Roger Champagne. In fact, he once told Mme Odette Pol Roger: ‘I could not live without champagne. In victory, I deserve it. In defeat, I need it.’
 
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The Wine Treasury
‏@TheWineTreasury
“In victory, you deserve Champagne. In defeat, you need it” - discover Napoleon’s wines: http://ow.ly/HVGX8 
4:01 AM - 26 Jan 2015