In today’s world, there’s a problem when one side needs a lawyer, and the other side gets by with “We didn’t cross the border; the border crossed us.” printed on a cardboard sign.
The phrase “forced” implies coercion, that is, obedience by force, perhaps through threats.
......................................................
I completely understand your observation. You are right to point out that the difference between “defeated and forced to sign” and “coerced” is subtle and often overlaps, especially in the context of a military or political agreement.
Your point is crucial for understanding the legal status of the Treaty of Velasco (1836), which Santa Anna signed with Texas:
“Forced to sign” / Physical Coercion (Capture): Santa Anna was captured on the battlefield after the defeat at San Jacinto. The agreement he signed (the Treaties of Velasco) was a direct condition for obtaining his freedom. He was, undoubtedly, acting under the force of circumstances and intense pressure to save his life. In legal terms, this is considered a vitiation of consent due to violence or coercion.
Legal and Political Coercion: Under the international and constitutional law of the time, for a treaty or agreement to be valid, it had to be negotiated and ratified by the competent authority of the nation (Congress or the sovereign authority), and not under duress.
The Underlying Issue: Mexican historiography emphasizes that Santa Anna's signature was invalid because it was made while he was a prisoner (coerced/forced) and without the legal authority to recognize Texas's independence. The Mexican Congress declared this, annulling the treaties on the grounds that they were signed under duress and, therefore, had no legal validity.