From 1803 on, the French also used the 3-arm Depillon semaphore at coastal locations to provide warning of British incursions.

English military engineer William Congreve observed that at the Battle of Vervik of 1793 French commanders directed their forces by using the sails of a prominent local windmill as an improvised signal station. Two of the four sails of the mill had been removed to resemble the arm of the new telegraph.