Complex sentence: Progress was slow and in October 1936 Gern had to leave Albert for Menton as he was sick and because of Gern's illness there was a delay in completion and Gern had to leave the final work to the Albert cement maker Joseph Gelmini.
Split into simpler sentences: Progress was slow and in October 1936 Gern had to leave Albert for Menton as he was sick. However because of Gern's illness there was a delay in completion and Gern had to leave the final work to the Albert cement maker Joseph Gelmini.