Complex sentence: First was the German Paul Grussfeldt and Norwegian Martin Ekroll summer 1888, then the Dane Carl Hall and the Norwegian mountain guide Mathias Soggemoen attempted in 1889.
Split into simpler sentences: First was the German Paul Grussfeldt and the Norwegian Martin Ekroll in the summer of 1888. The Dane Carl Hall and the Norwegian mountain guide Mathias Soggemoen attempted in 1889.