Born the second son of Karl von Weizsäcker and Marianne von Graevenitz. He joined the Infantry Regiment Nr. 9 and became a lieutenant. His brother Richard later joined the Regiment. Their unit crossed the border to Poland on September 1st, 1939. Heinrich died on the second day of the war, just a few hundred meters from his brother and was buried by him. He was later exhumed and moved to Stuttgart. A sculpture on the family grave made by his uncle Fritz von Graevenitz shows him on his deathbed.