It is said that they "commencer son feu de deux rangs".
The term "feu de deux rangs" refers to a method of firing described in 1791 regulations, not to the formation. In firing by this method, only the soldiers of the two first ranks should fire, first file by file starting from the right flank of each peloton, then, after the first shot, they should fire as fast as possible without any order. In other armies this method was called "fire by files". The soldiers of the third rank should not fire, they were to pass their muskets to the soldiers of the second rank, to take their muskets, to reload, and to pass again, and so on. Some officers said that in battle the soldiers of the third rank did not pass muskets to the second rank but fired themselves, usually over the heads of the two first ranks.