In the American Revolutionary War, which development directly led Franco American forces to lay siege to the British army at Yorktown in 1781?

Introduction / Context:
The siege of Yorktown in 1781 was the decisive battle that effectively ended major combat in the American Revolutionary War. Understanding why this siege occurred requires knowing what strategic move the British made and how American and French forces responded. Many exam questions ask which specific event led to the siege because it reveals how both sides thought about geography, supply lines and naval support.

Given Data / Assumptions:

• The question concerns the siege of Yorktown during the American Revolution.
• We are asked which development led to that siege.
• Options mention food supply, British occupation of Yorktown and authorization to end the war.
• We assume basic knowledge that General Cornwallis concentrated his troops at Yorktown on the Virginia coast.

Concept / Approach:
General Cornwallis moved his British forces to Yorktown, a coastal town in Virginia, partly to maintain a base near the sea and to be resupplied by the British navy. This decision gave American and French commanders an opportunity. With the French fleet blocking escape by sea and American and French troops surrounding Yorktown by land, they were able to trap Cornwallis. The siege followed directly from the British occupation and fortification of the town. While supply issues and wider strategy mattered, the key triggering event was the British move to Yorktown itself.

Step-by-Step Solution:
Step 1: Recall that Cornwallis gathered his army at Yorktown and built defenses there.Step 2: Understand that American and French commanders, including Washington and Rochambeau, saw this as an opportunity to concentrate their forces against him.Step 3: Note that the French fleet sailed to block the Chesapeake Bay, cutting off British naval support and escape.Step 4: Recognise that the combination of land and sea operations turned Yorktown into a trap, leading to the siege.Step 5: Among the options, identify the British occupation of Yorktown as the specific step that made the siege possible.Step 6: Reject options that either describe long term supply restrictions without naming Yorktown or that claim there was a prior agreement simply to end the war there.

Verification / Alternative check:
Historical narratives describe how Cornwallis dug in at Yorktown and how Washington changed his plans, moving from a possible attack on New York to a joint campaign in Virginia. The decisive French naval victory in the region and the construction of allied siege lines around Yorktown all followed the British presence there. There is no record of an early authorization that everyone would end the war peacefully at Yorktown. This confirms that the occupation of Yorktown by the British commander was the direct trigger.

Why Other Options Are Wrong:
Option A is too vague, since general supply problems existed throughout the war and did not on their own cause the specific siege at Yorktown. Option C is incorrect because there was no advance authorization by all parties to end the war at Yorktown; the siege was a military operation, not a prearranged ceremony. Option D is wrong because it treats all the listed factors as equal direct causes, whereas the clear and immediate reason for the siege was Cornwallis positioning his army at Yorktown.

Common Pitfalls:
Students sometimes blur the difference between long term pressures, such as supply shortages, and direct tactical decisions like choosing a particular town as a base. Another pitfall is to imagine that all major events were the product of formal agreements rather than battlefield conditions. To avoid these errors, focus on the specific move that created a military opportunity. In this case, the move to Yorktown gave the allies a clear target for a decisive siege.

Final Answer:
The event that led to the siege of Yorktown was the British decision to occupy and fortify Yorktown, Virginia, under General Cornwallis.