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This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

With Burma preoccupied by the Chinese threat, Ayutthaya recovered its territories by 1770, and went on to capture Lan Na by 1776. Burma and Siam went to war until 1855, but all resulted in a stalemate, exchanging Tenasserim (to Burma) and Lan Na (to Ayutthaya). Faced with a powerful China and a resurgent Ayutthaya in the east, King Bodawpaya turned west, acquiring Arakan (1785), Manipur (1814) and Assam (1817). It was the second-largest empire in Burmese history but also one with a long ill-defined border with British India.
Output:
What was the event called that caused Ayutthaya to reclaim lost territories ?