This is a huge topic. Despite the old quote that war never changes, warfare changed completely multiple times during our known history.

Two standard books (that cover the philosophy part) are Carl von Clausewitz On war and Sun Tzu The Art of war

Both cover general ideas about warfare which remained throughout history and parts that applied to their respective period and are more or less moot now (especially Clausewitz) But both are still somewhat up to date and definitely an interesting read. Sun Tzu also covers a great deal about leadership, without connection to warfare.