Original sentence: The Line Infantry was the remaining body of musket-armed foot soldiers.The seventeenth and eighteenth centuries saw expansion of the roles of the infantry, specialist grenadiers appeared and the role of skirmishers expanded
Edited sentence: The seventeenth and eighteenth centuries saw expansion of the roles of the infantry.To this end, the companies stationed on each flank of an infantry battalion were specialist units, with a company of light infantry trained as skirmishers to operate independently on the battlefield, and a company of grenadiers, who were usually the biggest and strongest men in the battalion, operating as the lead assault troops