During episodes of bad weather on long journeys from Stonington Island in 1948 and 1949, Fuchs had begun to develop plans for an expedition to cross the Antarctic from the Weddell Sea to the Ross Sea. This had previously been attempted, unsuccessfully, by Wilhelm Filchner in 1911 and by Ernest Shackleton in 1914.
In April 1955 Fuchs took leave from the Bureau to plan and undertake the Trans-Antarctic Expedition. There was much to do. Financial support had to be secured - some £725,000 (about £10 million today). He received support from his old friend and tutor at Cambridge, James Wordie, but was opposed by many in the British polar / geographical establishment, some seeking funds for the FIDASE.
However, Sir Winston Churchill supported his plans and eventually the Treasury, the governments of New Zealand, Australia and South Africa, were won over and gave their support. After the UK, New Zealand contributed the most, so was given the decision to select the leader of the Ross Sea Party and Scott Base, and chose Sir Edmund Hillary.
There were three components to the expedition: the Advance Party, who landed on the Filchner Ice Shelf at the head of the Weddell Sea; the Ross Sea Support Team, who laid depots from McMurdo Sound in the Ross Sea to the South Pole; and the Expedition party, led by Fuchs. Field teams included men from Britain, New Zealand, Australia and South Africa.
The expedition ship Theron carrying Fuchs and the Advance Party, was delayed by pack ice and so the unloading of stores could not begin until the end of January 1956 - very late to be so far into the ice on a small ship. In 1955 - 56 a base site at McMurdo Sound was established for the New Zealand team, and Scott Base was built. The main party arrived at Shackleton Base in January 1957 and at the beginning of October vehicles left to pioner the unknown route to South Ice, taking 59 days negotiating huge crevasses in appalling conditions.
On 24th November 1957 Fuchs and a team of 19 men with Sno-Cats and dog teams left Shackleton Base to begin the crossing of the Antarctic. Over challenging terrain the team encountered crevasses and they conducted scientific programmes, often travelling no more than 2 to 3 miles per hour, but averaging 22 miles per day, arriving at the South Pole on 19th January 1958. Meanwhile the Ross Sea party, led by Sir Edmund Hillary, departed Scott Base over easier terrian, reaching the South Pole ahead of Fuchs on 5th January. It was late in the season and conditions were difficult - Hillary urged Fuchs to break his journey at the Pole and finish it the following season, but Fuchs and his men continued with determination to complete the crossing as planned. On 2nd March 1958, Fuchs's team arrived at Scott Base in McMurdo Sound - a total journey of 99 days over 2158 miles.