Always be on the alert, be ready to fight

常备不懈 立足于打
Changbei buxie lizu yu da
Always be on the alert - Be ready to fight
1970, August
Shanghaishi chuban gemingzu (上海市出版革命组)
78x107 cm.
BG G2/668

The text in the image: No matter whether the enemy comes by day or night, make sure he will never come back (不管敌人白天来黑夜来,定叫它有来无回).