There are few practicable passes, the easiest being the famous Kokoda Track which crosses the range between Port Moresby and Buna and was in use for more than 50 years as a regular overland mail-route.

They took nearly five weeks to cover the 130 miles (210 km) track over extraordinarily difficult jungle terrain, from 14 October to 20 November 1942.

As a rule, the only way the troops could get up these ridges, which were steeper than along the Kokoda Trail, was either on hands and knees, or by cutting steps into them with ax and machete.

To rest, the men simply leaned forward, holding on to vines and roots in order to keep themselves from slipping down the mountainside.

It was largely due to the impossibility of transporting heavy equipment across the range that the Japanese failed to secure Port Moresby as a base early in 1942.