Continuous Cremaillere Line at Bird's Point, Missouri

Almost every engineering manual of the period constructed cremaillere or regular indented lines differently and almost all of them wound up with pretty much the same results: long branches alternating with shorter flanks that created a rather effective pattern of over-lapping columns of fire. The method offered here is something of a conglomerate of several different methods that seems to get the job done in the fewest possible steps.

Draw a right line of any length to establish the front boundary line and mark equi-distant points along the line. These points of division mark the location of the line's salient angles or points where the advanced ends of the long branches (or faces) will intersect advanced extremities of the flanks. In this case the salients will be 100 yards apart.

Drop perpendicular lines from each point of division toward the rear or unengaged side of the front boundary line. In this case the perpendiculars have been drawn 30 yards long. It is probably important to note that unlike the previously explained tenaille line constructions, these perpendiculars do not correspond to the capitals of the indented line's salient angles. These are merely construction lines that will make it much easier to establish the position and angle of the flanks.

Produce diagonal lines from the points of division on the front boundary line to the interior extremities of collateral perpendicular lines. These lines mark the positions of the indented line's long branches.

Produce the lines of the indented line's flanks by dropping perpendicular lines from the points of division on the front boundary line to collateral long branches. In this case the construction presented in the section on practical constructions for drawing a perpendicular line near the extremity of a right line has been used (the red circles denoting the constructions). The perpendicular lines thus produced are extended to their intersections with the long branches. These lines mark the positions of the indented line's flanks.

For the final step the extra constructions lines are erased and those parts of the lines used to mark the long branches that fall to the rear side of the lines of the flanks are also erased. This construction using 100 yard distances between salients on the front boundary line and a perpendicular 30 yards long produces long branches that are 95 yards long and flanks that are 29 yards long. This trace would require 248 men to man the interior crest in two ranks for every 100 lateral yards of front covered by the line. Salients are well within effective range of small arms fire delivered from the flanks.