If the attacking line, or reserve, consists of only one platoon, it is led by its chief; if it consists of two or more platoons, it is led by the senior chief of platoon or by the captain.
When a chief of platoon takes post as leader of two or more platoons, his place as platoon leader is taken by the corresponding file closer. Whenever the rally or assembly is ordered, the captain may cause the guidon to be displayed at the rallying or assembly point indicated.
640. In instruction exercises the enemy must always be outlined or represented by troopers, who may carry flags, under command of an officer or noncommissioned officer. In the beginning of this instruction these men will occupy fixed positions; later they will be instructed to ride so as to represent the movements of an aggressive enemy. The captain will explain to the commander the object of the exercise and tell him what to do.
641. The platoons of the attacking line may attack in one line or successively, as from column of platoons with extended distances. The captain, in addition to designating a reserve, may direct one or more platoons to execute any special mission. In the absence of special instructions from the captain the leader of each platoon, or combination of platoons, that is acting separately uses his discretion, endeavoring so to employ his command as best to assist in carrying out the general plan indicated by the captain's orders.
642. The reserve, in the absence of special instructions, follows the attacking line at from 100 to 150 yards in readiness to support the attacking line, meet a counter attack, or press the pursuit, as occasion may require.
A platoon designated for a flank attack is so conducted by its leader as to fall opportunely upon the enemy's flank.
If a flank platoon be so designated, it attacks from that flank unless otherwise directed.
To guard against a flank attack or an enveloping attack the captain may detach a platoon to move to the threatened flank so as to take an enveloping attack in flank or meet a flank attack. If a flank platoon be so designated, it acts on the corresponding flank unless otherwise directed. When no platoon is specially designated for flank guard, the corresponding duties fall upon the reserve.
643. The captain's commands should include an indication of the objective, unless the latter is obvious, designate the elements of the attack, and state any special mission that is assigned to any element. The captain's orders also usually include an indication of the weapon to be used by the several elements of the attack and may prescribe the formations to be employed. All details not prescribed by the captain are left to the discretion of the commanders of the several elements into which the attack is divided.
Where the same weapon is to be used by all it is ordinarily drawn at the captain's orders before the instructions for the attack are given. Otherwise, each commander gives the proper orders for drawing saber or raising pistol.