 Since early 1792 France had been at war with four of its neighbours on two fronts , battling Austria and Prussia in the Austrian Netherlands , and the Austrians and <unk> in Italy . On 2 January 1793 , almost one year into the French Revolutionary War , republican @-@ held forts at Brest in Brittany fired on the British brig HMS <unk> . [ Note B ] A few weeks later , following the execution of the imprisoned King Louis XVI , diplomatic ties between Britain and France were broken . On 1 February France declared war on both Britain and the Dutch Republic . 
