Question: In what year did Henry I of Castile's grandather sign a peace treaty guaranteeing his successorship to the throne of England?
Sentence (from "Treaty of Taipei"): This treaty was necessary, because neither the Republic of China nor the People's Republic of China was invited to sign the Treaty of San Francisco due to disagreements by other countries as to which government was the legitimate government of China during and after the Chinese Civil War.
Relevant evidence: No