As others have said it is for camoflage and glare..... even at night. On that note notice that the military is using rough no shine boots as opposed to the old shiny or smooth ones which give more reflection with night vision gear.
But what others didn't mention is that though color and blending in is important it is not the most important.
The human brain has an amazing ability to pick out a human face in a landscape or while trying to process a huge amount of visual data. Of course this is an ingrained survival mechanism. So what face paint does is visually break up the shape of the face. Think say a dark line starting at the hairline, a third of the way across. The line countinues down to the eye, continues down the middle of the cheek and then veering sharply across the mouth down to the middle of the chin. Then when someone is looking at you it is harder to discern the face, cheek, nose and chin combination that the brain processes to identify another human.
U.S. Military - Paint- Face - Camouflage- Compact - 4- Color with Mirror , 5 COLOR CAMOUFLAGE FACE PAINT MILITARY ISSUE #4500 BOBBIE WEINER ENT, Army Camouflage 3 Colour Face Paint Make~Up Military Rambo Soldier Fancy Dress , vintage camouflage Face Paint Stick -green and loam, Camouflage Face Paint US Army Issue Camo with Mirror, 3 COLOR CAMOUFLAGE FACE PAINT MILITARY ISSUE ACU #ACU1 BOBBIE WEINER ENT, 3 COLOR ACU CAMOUFLAGE FACE PAINT STICKS MILITARY ISSUE BOBBIE WEINER ENT, 3 COLOR CAMOUFLAGE FACE PAINT MILITARY ISSUE JUNGLE #1011 BOBBIE WEINER ENT, SNAZAROO Military Camouflage FACE PAINT Jungle Tiger, 10 X British Military Issue 3 Colour Camouflage Face Paint Balling Hunting Camo, USMC Army Military Issue Surplus CAMOUFLAGE FACE PAINT Light Green Loam NEW USGI, SNAZAROO CAMOUFLAGE FACE PAINT KIT 3 COLOURS Fancy Dress Make Up, Genuine GI 4 Color Camouflage Camo Face Paint Kit, 3 COLOR WOODLAND CAMOUFLAGE FACE PAINT STICKS MILITARY ISSUE BOBBIE WEINER ENT, military wargame four colors paint face camouflage camo skin oil, One Camouflage makeup 5 color camo face paint 5 color camo makeup signal mirror , 4 COLOR CAMOUFLAGE FACE PAINT MILITARY ISSUE #6000 BOBBIE WEINER ENT, MULITCAM 4 COLOR CAMOUFLAGE FACE PAINT MILITARY ISSUE #MULTI BOBBIE WEINER ENT, 1 Stick Camouflage Face Paint Nato Light Green & Loam, USGI CAMOUFLAGE FACE PAINT LIGHT GREEN AND LOAM MILITARY CAMO STICK METAL TUBE, WOODLAND 4 COLOR CAMOUFLAGE FACE PAINT MILITARY ISSUE #4000 BOBBIE WEINER ENT, 3 COLOR WOODLAND CAMOUFLAGE FACE PAINT TUBES MILITARY ISSUE BOBBIE WEINER ENT, Genuine Camo Face Paint Camouflage Stick Colors Light Green and Loam Hunting, Genuine Camo Camouflage Face Paint Stick Colors Light Green and Sand Hunting, Genuine Camo Camouflage Face Paint Stick Colors White and Loam Paintball Hunting, New Snazaroo Face + Body Paint Kit! Various Theme Sets!, New US Made GI Type Multicam Camouflage 4 Color Face Paint Compact w/ Mirror, US Army Military 3-Color Camouflage Face Paint Compact NEW, Military Camouflage Camo Woodland Face Paint Stick 3pcs W/3 Colors, Camo Face Paint Stick Genuine GI Woodland Camouflage, SNAZAROO Camouflage Theme Pack FACE PAINT PAINTING-Kid, Camouflage ~ CAMO FACE PAINT ~ Easy On Easy Off Hunting, Vintage GI Joe Paper Advertising Camouflage Face Paint Manual ! , WWII U.S. ARMY D-DAY CAMOUFLAGE / FACE PAINT STICK ORIGINAL UNISSUED MINT , US Army Military GI All-Purpose Camouflage Face Paint Compact NEW, Face Paint - FLECKTARN - German Army Camouflage - GREEN, US Army USMC Airsoft Military Camo Camouflage Face Paint Creme Tubes (3 Tubes!), US Army USMC Airsoft Military Camo Camouflage Face Paint Creme Tubes (3 Tubes!), NEW TonyMoly for Men *Dandy Guy Camo Cream* Military Camouflage Cream Face Paint, British Forces Issue BCB Chameleon 3 Colour Camo Camouflage Face Paint , New Rothco GI Type Woodland Bark Camouflage 5 Color Face Paint Compact w/ Mirror, New Rothco GI Type Army Digital Camouflage 3 Color Face Paint Compact w/ Mirror, New Genuine GI Woodland Camouflage Face Paint Stick - Current US Issue!, **NEW** Genuine USA MIL 4 Colour CAMOUFLAGE FACE PAINT Compact **NEW**, New Hunter's Specialties 3-Color Woodland Camouflage Makeup Face Paint Kit 00260, 8 NWT Juicy Couture Kids Face Paint Purple Camouflage Shorts Eyelet Ruffle Trim, Face Paint Camouflage Camo Stick Military Light Green and Loam, Mossy Oak Hunting Make Up Camo Camouflage Face Paint Army Paintball NIP MO, GENUINE G.I. WOODLAND CAMOUFLAGE FACE PAINT STICK MADE IN THE USA 8201, Camouflage ~ CAMO FACE PAINT ~ Easy On Easy Off ~ Fall,
