Final answer:
The fall of Port Hudson was significant because it was the last Confederate stronghold on the Mississippi River to surrender, giving the Union complete control over the river.
Step-by-step explanation:
The fall of Port Hudson was significant because it was the last Confederate stronghold on the Mississippi River to surrender. It happened in 1863, and with this surrender, the Union gained complete control over the river, which was a crucial strategic advantage.
Taking Vicksburg and Port Hudson effectively cut the Confederacy in two, and this was an important step for the Union to win the war.