One of the things I often do is listen to various lectures, symposiums, talks, etc. on military history. Particularly when the workday is a slow one, it is mentally stimulating while otherwise doing uninteresting work. Are there any Youtube channels, presenters, organizations, etc., that one could recommend along these lines? The eras I'm most interested in the conflicts in the interwar period (e.g., invasion of Abyssinia, the Spanish Civil War, the The Second Sino-Japanese War, etc.), the Second World War, and the Cold War. (Though I am interested in most history, military or otherwise.) Thanks much.