In 1947, President Harry Truman unified various parts of the US Armed Forces under a single chain of command, and in 1950 he dedicated a day to commemorate them all — the third Saturday of May.
Now the US Armed forces employ over 1.3 million people: they are the biggest and most advanced in the world.
From May 19th (9:00 GMT) until May 22nd (9:00 GMT), play 3 battles using American vehicles (rank III or higher, with an activity of not less than 70%) to receive the “National Armed Forces Day” decal.
Complete the task in random battles, except for Enduring Confrontation missions and [Assault] mode. Track your progress in the hangar by clicking Nickname → Achievements → Holidays → US Armed Forces Day.
“National Armed Forces Day” decal
You can find the decal in the “Holidays” tab in the Customisation menu.