France declared war on Britain in 1793 (War of First Coalition). What was its motivation for declaring war? It was already at war with many European powers at the moment, and it was not likely in a position to defeat or conquer Britain. I understand if Britain had motivation to be at war with France (e.g. to stop republicanism or the French conquests in Europe), but I don't know what was to be gained by France from this. Wouldn't it be better to let Britain be neutral and deal with them later if needed?
According to the OP's own link, "Britain began military preparations in late 1792 and declared that war was inevitable unless France gave up its conquests, notwithstanding French assurances they would not attack Holland or annex the Low Countries."
France felt that she needed the outposts that she had captured in (modern) Belgium to further her Revolution. Britain was opposed to any such French expansion, and France knew that war was inevitable. Over a century later, in 1914, Britain and Germany went to war for essentially the same reason.
Being the "revolutionary" country, France wanted to make the first "declaration" and strike the first blow.