Complex sentence: The September 1944 Hyde Park Agreement extended both commercial and military cooperation into the post-war period, but Roosevelt died on 12 April 1945, and the Hyde Park Agreement was not binding on subsequent administrations.
Split into simpler sentences: The September 1944 Hyde Park Agreement extended both commercial and military cooperation into the post-war period. But Roosevelt died on 12 April 1945, and the Hyde Park Agreement was not binding on subsequent administrations.