This 1944 cover photo shows Chinese engineers constructing a hand-made wooden bridge across the Tanai Hka River in Myanmar (then called Burma).

The bridge was a key crossing for the Ledo Road, a critical overland route for the Allies supplying Chinese forces in World War II.

The road started at Ledo, the railhead in northeast India, crossed the 9,000-ft Patkai Hills in northern Myanmar, went through the Hukawng Valley, crossed the Irrawaddy River and joined with the Burma Road at Mong-Yu.

Chinese and Indian laborers and American military engineers struggled to cut the route through wild jungles, deep valleys and swamps.

The work force peaked at 30,000. Mud, malaria and Japanese snipers took their toll. The 465-mile-long, two-lane gravel route was completed in late 1944.