Complex sentence: Oslo had unsuccessfully bid to host the 1936 Winter Olympics, losing to Germany, who had hosted the 1936 Summer Olympics; at that time the nation that hosted the Summer Olympics also hosted the Winter Olympics.
Split into simpler sentences: Oslo had unsuccessfully bid to host the 1936 Winter Olympics, losing to Germany, who had hosted the 1936 Summer Olympics. At that time the nation that hosted the Summer Olympics also hosted the Winter Olympics.