Like their US Army counterparts, the US Marines needed the ability for their units to be able find their own personnel quickly. This was essential for a fighting force to maintain cohesion in a battle, especially in something as chaotic as a beach landing where a force could become scattered and intermingled with neighboring units.


USMC helmet and cover marked to a 4th Marine Division Private in the 25th Marine Regiment, 3rd Battalion, I Company

The US Marine Corps developed a marking system that would hide the identity of individual units from the enemy, but could also be quickly distinguishable to friendly forces. Known as the Unit Numerical Identification System (UNIS), these stenciled markings were a series of numbers placed inside or nearby a geometric symbol or insignia. Just like the famous 101st Airborne Division’s use of playing cards on their helmets to identify their men, the US Marine’s UNIS marking let Marines find their fellow soldier in the heat of battle.

All six marine divisions utilized UNIS markings as well as supporting artillery and amphibious units. Most divisions and units marked gear, vehicles and supplies but uniform marking was most prevalent with the 4th and 5th Marine Divisions. The 4th Marine Division used a half moon mark and the 5th Marine Division used a rectangle.


4th Marine Division cover marked to the 25th Marine Regiment, 3rd Battalion, I Company


USMC Musette bag with markings to the 4th Marine Division Medical Battalion Headquarters

Markings varied in shapes and sizes and their usage was not always uniform. The 4th Marine Division marked their field equipment like canteens, bags and other items as well as their jackets and pants while the 5th Marine Division markings were almost exclusively on shirts.

4th Marine Division markings were not always uniform as some soldiers marked most of their gear and some almost none at all. UNIS markings on items like uniforms also had a number representing the rank of the soldier whereas items like canteens might not have a rank since they technically belonged to the company rather than an individual soldier.

UNIS markings can be commonly seen being worn by marines at the momentous battles of Saipan and Iwo Jima as well as in the occupation of Japan.


Shirt from a 4th Marine Division Private from the 4th Engineer Battalion, HQ & Service Company


4th (left) and 5th (right) Marine Division marked camouflage ponchos. The 4th Marine Division marking is to the 23rd Marine Regiment, 1st Battalion, A Company. The 5th Marine Division Marking is to the 13th Marine Regiment (Artillery) 4th Battalion, L Battery


Shirt from a 5th Marine Division Technical Sgt. from the Division Headquarters Battalion

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