Complex sentence: From time to time, during the late twenties and early thirties served as legal adviser to the delegation at the League of Nations on arms limitation where had the opportunity to meet with Hitler, Mussolini, Litvinov and the leaders of Britain and France.
Split into simpler sentences: From time to time, during the late twenties and early thirties, he served as legal adviser to the delegation at the League of Nations on arms limitation. There had the opportunity to meet with Hitler, Mussolini, Litvinov and the leaders of Britain and France.