Final answer:
The Allied forces were unable to use airplanes in the Argonne Forest due to difficult terrain, limited visibility, and the presence of anti-aircraft defenses.
Step-by-step explanation:
The Allied forces were unable to use airplanes during the fighting in the Argonne Forest due to several reasons:
- The forested and hilly terrain made it difficult for airplanes to take off and land, limiting their effectiveness in providing air support.
- The dense vegetation in the forest hindered visibility, making it challenging for pilots to accurately identify targets and coordinate with ground troops.
- The presence of enemy anti-aircraft defenses and the risk of friendly fire also discouraged the use of airplanes in this particular battle.