Who first declared themselves to be the National Assembly?

Sieyès

On 17 June 1789, the Communes approved the motion made by Sieyès that declared themselves the National Assembly by a vote of 490 to 90. The Third Estate now believed themselves to be a legitimate authority equal to that of the King.

Hope this helped :3

it foreshadows the theme of the paragraph and hints the topic that will be discussed in the paragraph!