At the end of the 1940s, Rhaetian Railways (RhB9 had to urgently modernize and enlarge their rolling stock, especially the engines. Their 15 locomotives of the Ge 6/6 I series, built in the 1920s and famous under their nickname "Crocodiles" due to their protruding two snouts on both sides of the cab, were not capable anymore of hauling the long and heavy trains on the steep grades of the network with the necessary speed, 1947 and 1953, ten modern powered bogie locomotives were delivered as the Ge 4/4 I series. With a maximum power of 1600 hp, these locomotives soon reached their limits as well after a few years, and an even larger, more powerful locomotive series was needed.
The solution was a six axle locomotive (Bo-Bo-Bo or 4-4-4 arrangement), using many of the proven components of the four axle Ge 4/4 I series. Technically the design was modern for the time being: low voltage on-load tap changer, single-phase series-wound motors. The outer two bogies and the motors could be exchanged with the Ge 4/4 I. The locomotive body was cut in the middle and articulated, allowing rotation around the lateral axis in order to easily handle track slope changes.
The Ge 6/6 II are capable of speeds up to 80 km/h and have a mass of 65 metric tons. They power output is at 1776 kW or 2400 hp at a reference speed of 46 km/h respectively. Their towing capacity ist at 205 metric tons on 45‰ grades and 280 tons on 35‰ grades. The middle bogie kann move sideways to allow sharper turn radii.
The first two locomotives were delivered in 1958 by Swiss companies SLM, BBC and MFO at a price per locomotive of 230'000 CHF. They were assigned the numbers 701 and 702 and were christened to the names of Raetia and Curia (the roman latin names of the canton/district as well as the district capital city)
The two pilot production locomotives performed very well, thus five more were ordered and delivered in 1965. They were 200'000 CHF more expensive than the first two locomotives, and given the numbers 703–707.
Engine 701 carried the name of the Roman province Raetia, which up to this day is synonymous with the canton of Grisons/Graubünden, where the RhB operates. Locomotive 702 was christened to the Roman latin name of the capital city of Chur, Curia. The other five engines were given the names of larger villages located at the end of the main lines of RhB. Beside the name, every locomotive carried their number and a coat of arms of the respective village (loco 701 carried the coat of arms of the Canton Grisons/Graubünden).
Technically, all Ge 6/6 II are identical. The first two engines had three smaller front windows and a narrow door on both front sides to allow passage from one locomotive to another. These doors were weld shut later, and the further five locomotives were delivered with only two larger windows and no front side door.