Given the task definition and input, reply with output. 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.

In 1814, a secret organization called the Filiki Eteria (Society of Friends) was founded with the aim of liberating Greece. The Filiki Eteria planned to launch revolution in the Peloponnese, the Danubian Principalities and Constantinople. The first of these revolts began on 6 March 1821 in the Danubian Principalities under the leadership of Alexandros Ypsilantis, but it was soon put down by the Ottomans. The events in the north spurred the Greeks of the Peloponnese into action and on 17 March 1821 the Maniots declared war on the Ottomans.
In which year did the Society of Friends begin?