I found this picture the other day of my grandfathers unit. When my grandfather was alive he never talked about it. I'd just like to know what did that unit do in WWII? Any info would me much appreciated!!
At first glance, it would appear your photo is slightly mislabeled. The 126th Infantry Regiment was part of the 32nd Infantry Division.
The only 126th Battalion in the US Army during WWII was the 126th Field Artillery Battalion, also opportunately assigned to the 32nd Division; however their subunits were called batteries, not companies.
So, taking into account the mislabeling, it appears your grandfather served in Company B, 1st Battalion, 126th Infantry Regiment, assigned to the 32nd Infantry Division.
The 32nd Infantry Division was a National Guard division made up of troops from Michigan and Wisconsin. They accumulated the most combat days (654) of any US division during the war, and were among the first Army units to fight the Japanese in the Pacific. They also helped drive the Japanese from Leyte and Luzon in the Philippines during the first half of 1945. 11 soldiers from the division (including 2 from the 126th Infantry Regiment) were awarded the Medal of Honor.
The 126th Infantry Regiment's 2nd Battalion marched 130 miles over the Owen Stanley ridge in brutal jungle conditions to attempt to cut off the retreating Japanese in New Guinea in October 1942; they did not see a single Japanese soldier during their march, and the depleted unit was thrown into combat immediately after arriving at the front.
Sources:
http://www.32nd-division.org/history/32hist.htm
http://www.32nd-division.org/history/ww2/32ww2-11.html
http://www.ibiblio.org/hyperwar/USA/USA-P-Papua/index.html
http://www.history.army.mil/html/forcestruc/cbtchron/cc/032id.htm