Complex sentence: At the beginning of his political career, Hitler was hostile to Britain as one enemies of the "Reich", but strongly influenced by the British opposition to the French occupation of the Ruhr in 1923, Hitler came to rank Britain as a potential ally.
Split into simpler sentences: At the beginning of his political career, Hitler was hostile to Britain, considering it an enemy of the "Reich". However, strongly influenced by the British opposition to the French occupation of the Ruhr in 1923, Hitler came to rank Britain as a potential ally.