From the Forgotten Airfield Website:

This memorial is to commemorate the Y-29 Zutendaal Air Base. The air base was construct in November 1944 by the USAAF IX Engineer Command, 852nd and 846th engineer Aviation Battalion. The air field consisted of a number of tents for housing, a fuel and ammo dump, food and water supplies and an electrical grid for communications and illumination. 

The following groups were stationed there:

366th Fighter Group (P-47 Thunderbolt): November 19, 1944 to April 11, 1945

352nd Fighter Group (P-51 Mustang): December 1944 to February 1945 (moved to Y-84)

406th Fighter Group (P-47 Thunderbolt): February 8, 1945 to April 15, 1945

391st Bomber Group (B-26 Marauders): April 1945 to May 27, 1945

The airfield was closed and abandoned on June 20, 1945. Today, all that remains is a memorial in a wooded area where Y-29 used to be. The monument is located near the spot where the end of the runway used to be.

In November 1944 a new airfield near the World War I aerodrome was constructed by the United States Army Air Forces IX Engineer Command, 852nd and 846th Engineer Aviation Battalions. Known as Advanced Landing Ground "Y-29", the airfield consisted of a single 5000 foot (1500m) Sod runway aligned 06/24. In addition, tents were erected for billeting and also for support facilities; an access road was built to the existing road infrastructure; a dump was created for supplies, ammunition, and gasoline drums, along with a drinkable water; and a minimal electrical grid for communications and station lighting was installed.

Asch (Zutendaal) was home to North American P-51 Mustangs of the 352nd Fighter Group, Eighth Air Force (which included the 328th Fighter Squadron, led by George Preddy); and P-47 Thunderbolts from 366th Fighter Group, Ninth Air Force, from 19 November 1944 – 11 April 1945. The 406th Fighter Group, also flew from the airfield in P-47s from 8 February – 15 April 1945. The fighter planes flew support missions, patrolling roads in front of the beachhead; strafing German military vehicles and dropping bombs on gun emplacements, anti-aircraft artillery and concentrations of German troops when spotted.

On January 1, 1945, Asch airfield was the site of a major aerial battle during the Luftwaffe's Operation Bodenplatte. The FW-190's and Bf-109's of JG-11 arrived at Asch just as the 487th FS of the 352nd FG were rolling down the runway, the ensuing battle came to be known as the Legend of Y-29 and encapsulated the failure of Operation Bodenplatte as a whole. The pilots of the 487th Fighter Squadron who took off did so under fire and in the face of overwhelming odds. The 487th scored 23 kills while suffering only 2 damaged aircraft in the face of 3:1 odds. For their performance the 487th received the only Distinguished Unit Citation given to a fighter squadron in the European theatre.

When the fighter units moved out, the 391st Bombardment Group flew B-26 Marauder medium bombers from the airfield until 27 May 1945. With the end of the war in Europe, the airfield was closed on 20 June 1945