“End the war before it ends you” is a peace slogan that has been printed on many images. “I’m sending you back, son, and I hope we end the war before it ends you” is a line in the 1936 play Johnny Johnson (the biography of a common man) by Paul Green.
 
One popular image of someone holding an “END THE WAR BEFORE IT ENDS YOU” sign is apparently from the “March on the Pentagon” on October 21, 1967, to end the Vietnam War.
     
       
Google Books
Johnny Johnson (the biography of a common man)
By Paul Green
New York, NY: Samuel French
1937
Pg. 67:
I’m sending you back, son, and I hope we end the war before it ends you.
 
Twitter
Steffy Tejeda
@Steffysara
End the WAR ..  before it ends you !
10:27 PM · Apr 20, 2011·Twitter Web Client
   
Twitter
Adriana Arrieta ϟ
@adrianarrietan
End the war before it ends you.
3:24 PM · May 3, 2011·Twitter Web Client
   
Twitter
FAN. FAN.FAN
@minnillolachey
Photo: END THE WAR BEFORE IT ENDS YOU http://tumblr.com/xan2e3ory7
9:37 PM · May 4, 2011·Tumblr
   
The Equinox
‘END THE WAR BEFORE IT ENDS YOU’
Thousands march on Washington in 1967 to protest the Vietnam War
Jessica Ricard
October 18, 2017
Just 50 years ago, thousands gathered in protest of a war that was killing thousands.1
 
On Oct. 21, 1967, upwards of 100,000 protesters assembled in Washington, D.C. to challenge the Vietnam War. About half the protesters marched all the way to the Pentagon, fighting for an end to the bloody battle that was currently taking place. Once they reached the Pentagon, 35,000 participated in a massive protest.
 
Goolge Books
Title End the War Before It Ends You: All Purpose 6x9 Blank Lined Notebook Journal Way Better Than a Card Trendy Unique Gift Black Solid Rebelion
Author Saffa Savage Gd
Publisher Independently Published, 2019
ISBN 1704198895, 9781704198897
Length 122 pages