Lastly, the real significance of the term “wave” lies in its application to the formation of the departure of the attack and during the first part of its advance into the interior of the hostile position. As soon as the assaulting echelons are held up by nests of resistance, they are obliged to halt while neighboring echelons on both flanks continue the advance. Also, reinforcing units will come up from behind to outflank such a nest. As soon as such a condition arises within the enemy’s position, the disposition of the troops in waves is lost and the fight is continued in the best formation possible under the circumstances. Formation of an Assaulting Battalion =Assaulting Companies.= In an assaulting company, a certain number of platoons are placed in the first or assaulting line, and the rest in the second line as reinforcing platoons. The assaulting platoons deploy usually in two lines of skirmishers, the different specialists being assigned to places in these lines depending upon their functions in the attack. The line of assaulting platoons is known as the line of combat. A third line of grenadiers follows closely behind the assaulting platoon, and may be called a part of it. These grenadiers are furnished by the reinforcing platoons and are known as trench cleaners. Their function does not begin until the hostile line is reached, and it is to clear out the trenches of the first line of the enemy while the assaulting troops continue their advance in the open ground. [Illustration: ATTACKING COMPANY THREE PLATOONS IN THE FIRST LINE] The reinforcing platoons are either deployed in lines of skirmishers or lines of small columns. These platoons constitute the line of reinforcement and follow the advance of the assaulting platoons at a distance of about forty to sixty yards. The machine guns detailed to the assaulting companies by the chief of battalion are placed with the reinforcing platoons and are usually carried on the flanks. Considering the battalion as the assaulting unit and adopting the term “wave” to designate each platoon, we may say that the company of the first echelon of the assault is disposed in two waves. The position of the captain is in front of the second wave between the two reinforcing platoons. His liaison group remains with him. =Supporting Companies.= The supporting companies of an assaulting battalion constitute the second echelon. These companies, also, are formed in two waves. These waves are formed like those of the reinforcing platoons of the assaulting company, either in deployed lines or in lines of small columns. Usually the battalion has two companies in the first line and two in the second line. In other words, the battalion carries out the assault in two echelons of two waves each, the distance between the two echelons being from 200 to 300 yards. In rear of the support companies and following their advance, are the remaining machine guns of the battalion and the 37 mm. platoon.