In 1935, while climbing at Breakneck Ridge on the Hudson River, Wiessner spotted the gleaming white quartzite cliffs of the Shawangunks in the distance.

Wiessner, often in partnership with fellow immigrant Hans Kraus, established numerous first ascents in the Gunks, including many climbs that are popular (and intimidating) to this day.

Wiessner had his first experience of climbing in the greater ranges when he was a member of the first German expedition to attempt the 8,126 m (26,660 ft) Nanga Parbat, led by Willy Merkl in 1932.

[1] Although the team were all strong climbers none had Himalayan experience, and poor planning (particularly an inadequate number of porters), coupled with bad weather, prevented progress far beyond the Rakhiot Peak northeast of Nanga Parbat's summit.

[4] On July 20, Wiessner and House first attempted the line of a great couloir that comes directly down between the main summit tower and the northwest peak.

It was an excellent line for quickly ascending but they were unable to traverse onto the south face proper due to poor rock conditions and were forced to retreat to base camp.

While Wiessner initially started in boots, he quickly changed to rope-soled shoes and gave his ice axe and extra rope to House.

They aborted their earlier plan of descending the shorter north face and retraced their ascent line, reaching their tent on the Dais Glacier at 2 am.

Wiessner recounted that, although the difficulties of the climb had been passed and the remainder was straightforward, he turned back in deference to the wishes of his sherpa, Pasang Dawa Lama.

[7] The controversy would be reignited after Durrance was convinced to release his personal expedition diary in 1989, which laid blame on the failings of both the deputy party leader Tony Cromwell and Wiessner.

[8] No one came as close to the top of the mountain again until July 31, 1954, when the first ascent was achieved by Lino Lacedelli and Achille Compagnoni on the 1954 Italian Karakoram expedition.

He was reportedly disappointed that he was not allowed to fight for the U.S. in World War II, serving instead as a technical advisor to the 10th Mountain Division, and to the "equipment for cold climatic areas commission" of the office of the Quartermaster General of the United States Army in Washington, DC.

His family, including his wife Muriel and children Andrew and Pauline, honored his legacy by continuing to participate in outdoor activities.

In recognition of his contributions, the Fritz Wiessner Woods was established as a memorial, and several climbing routes and areas have been named in his honor, ensuring that his influence on the sport endures.