INTRODUCTORY NOTES1. Machine guns, when in defence and when assisting in re-organization, must make preparations to fire on certain pre-arranged areas should the SOS be sent up during the night or should the arc of fire become obscured.
This pre-arrange fire is referred to as firing on fixed-lines. Fixed lines can only be selected and laid intelligently if commanders have a thorough knowledge of their use and of characteristics of beaten zones.
LESSON 105.- LAYING A FIXED LINE (FLANKING FIRE)
A – INSTRUCTOR’S NOTES
Aim
1. To teach how to lay a fixed line as near as is safe to a defended locality by flanking fire.
Class and instructors
2. Lecture – One officer instructor and not more than 30 in the class; Practice – Squads under squad instructors.
Periods
3. One 45-minute period, lecture; one 45-minute period, practice.
Stores
4. Lecture – Blackboard and chalk; Practice – Gun, tripod, dial sight, belt with drill cartridges and aiming post. Class require range tables.
Preparation
5. Draw the diagrams given below on the blackboard.
B – CONDUCT OF LESSONApproach
6. Give the aim of the lesson (see para 1).
7. Show the class that fixed lines, flanking fire, may take either of two forms:-
- (a) A belt of fire (see Fig 35 below). In this case, it will usually be necessary to give different elevations to each gun so as to make the belt of fire as long as possible. The elevations will be decided upon by consulting the range tables, so as to ensure that the beaten zones overlap. An example of this can be seen in Fig 35, where by ordering “No. 1 gun 500, No. 2 gun 700,” on flat ground the belt of fire can be stretch from 380 yards to 800 yards and the beaten zones yet overlap. This is one of the most valuable characteristics of the machine gun and should not be utilised to the fullest extent. When laying a belt of fire, tapping right and left is not normally employed.
- (b) At times it may be necessary to lay a fixed line on a bridge, cross-roads, narrow valley or some other place where the enemy is likely to concentrate. In such circumstances, it may be necessary to tap right and left in order to cover the whole width of the point to be engaged.
Rules
8. The rules for flanking fire apply to the laying of fixed lines, flanking fire. There are however differences in the application of certain of these rules. These differences are discussed below.
9. RULE TWO.- BARRELS MUST NOT POINT NOR BULLETS FALL WITHIN THREE DEGREES OF OWN TROOPS.
Show that this implies that a belt of fire must not be laid closer than three to degrees to any locality occupied by own troops. (See Fig 36).
10. RULE FIVE.- CAREFUL ALLOWANCE MUST BE MADE FOR WIND
Explain:-
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- If, when laying a belt of fire in front of own troops, the wind tends to blow the bullets within the three degree limit, the guns must be switched away from own troops.
Example 1:-
-
-
- Guns are required to lay a belt of fire in front of an infantry locality. A wind is blowing from 4 o’clock at 10mph.
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If the guns were laid only 3 deg from the locality, the wind would blow the bullets inside the 3 deg limit by 10 minutes. The guns must therefore be switched 10 minutes to the right.
Example 2:-
-
- If, in the previous example, the wind had been blowing from the left, ie, away from our own troops, the guns should be laid 3 deg from the locality. They could not be laid closer to the locality as, if the wind dropped suddenly, the bullets would fall within the 3 deg limit.
Procedure
11. Explain the procedure in laying a gun on a fixed line as near as is safe to a defended locality.
- (a) To lay the gun for direction.
- (i) The safety allowance required is 3 degrees.
- (ii) Set this angle on the deflection drums and, using the lensatic sight, lay on the front edge of the defended locality.
- (b) To lay the gun for elevation.
- (i) By running the tangent sight up and down, find the limit of flanking safety.
- (ii) Select a point either on or outside this line in the area where the group commander has ordered the fixed line to fall.
- (iii) Obtain the range to this point. Decide on the elevation to be given to each gun so that the fixed line will be as long as possible without there being gaps between the beaten zones.
- (iv) Lay the gun on the selected point with the necessary range on the tangent sight.
- (c) To maintain direction and elevation.
- (i) Set the direction dial at zero.
- (ii) Put out the aiming post and using the deflection drums, align the lensatic sight on it.
- (iii) Record on paper the quadrant elevation and the angle on the deflection drums. Place the paper in the dial sight box for safe keeping.
- (d) Half load and press the thumb-piece.
- (e) Any wind problem affecting the safety of own troops must be borne in mind, and before firing on the fixed line the necessary wind allowance must be made, using the deflection drums, and re-laying the guns on the aiming post.
Practice
12. Explain and demonstrate with the gun, laying a fixed line.
13. Practise the squad in working out problems and laying fixed lines.
14. Demonstrate that after arrangements have been made to lay the gun on a fixed line, the gun, if required, can fire on other targets and yet be placed back on the fixed line when necessary.
15. Further practice in fixed line problems, including wind problems.
Conclusion
16. Questions to and from the squad.
17. Sum up main points.
LESSON 106.- LAYING A FIXED LINE, OVERHEAD FIRE
A – INSTRUCTOR’S NOTES
Aim
1. To teach how to lay a fixed line as near as is safe to a defended locality by overhead fire.
Class and instructors
2. Lecture – One officer instructor and not more than 30 in the class; Practice – Squads under squad instructors.
Periods
3. One 45-minute period, lecture; One 45-minute period, practice.
Stores
4. Lecture – Blackboard, and chalk; Practice – Gun, tripod, dial sight, belt with drill cartridges and aiming post. Class require range tables.
Preparation
5. Draw the diagram given below of the blackboard.
B – CONDUCT OF LESSONAim
6. Give the aim of the lesson (see para 1 above).
7. State that there may be occasions when it is desired to lay a mat of fire over the heads of own troops. In this case, the guns are laid a certain distance apart, normally 50 yards. Arrangements are made to tap the guns right and left so that the width of the mat is 100 yards (see Fig 38 above).
Rules
8. Tell the class that the rules for overhead fire apply to the laying of fixed lines, overhead fire.
Procedure
9. Describe the procedure for laying a gun on a fixed line (overhead fire) as near as is safe to a defended locality:-
- (a) Obtain the range to the defended locality, and from the range tables obtain the equivalent range. Convert 25 yards at the equivalent range to an angle by means of the VI graph. Bring this angle to the nearest number of taps, if it does not come to an exact number, take it to the next highest.
- (b) To lay the guns for direction.
- (i) Set the angle obtained above on the deflection drum of the dial sight of No. 1 gun as right and of No. 2 gun as left.
- (ii) Lay both guns by means of the lensatic sight on the centre of the defended locality. The direction of No. 1 gun is now 25 yards to the right of centre and of No. 2 gun 25 yards to the left of centre.
- (c) To lay the guns for elevation.
- Set the equivalent range on the tangent sight and lay the guns on the defended locality.
- (d) To maintain direction and elevation.
- (i) Put out the aiming post. Using the direction drums, align the lensatic sight on it. Zero the tripod direction dial.
- (ii) Record the quadrant elevation.
- (iii) Note on paper the QE, the angle on the deflection drum and the number of taps right and left. Place the paper in the dial sight box for safe-keeping.
- (e) Half load and press the thumb-piece.
- (f) Any wind problem affecting the safety of own thumbs must be calculated on the equivalent range. Before firing on the fixed line the necessary wind allowance must be made, using the range drum and relaying the gun.
Winds
10. Explain that head and rear winds will affect the laying of overhead fixed lines as follows:-
- (a) Head winds will tend to slow up the bullet and cause it to drop below the safety angle. The equivalent range will therefore have to be increased accordinly.
- (b) Rear winds will entail no adjustment to the equivalent range.
Practice
11. Revise the squad in the method of opening up the lines of fire to 50 yards apart and of calculating the number of taps required.
12. Revise the equivalent range.
13. Demonstrate the laying of a fixed line.
14. Practise the squad in calculating and laying a fixed line.
15. Demonstrate that, after arrangements have been made to lay guns on fixed lines, the guns can if required engage targets within the arc and yet be placed back on fixed lines if necessary.
16. Further practice, including wind problems.
Conclusion
17. Questions to and from the squad.
18. Sum up main points.
LESSON 107.- LAYING A FIXED LINE WHEN NO DAYLIGHT RECONNAISSANCE HAS BEEN POSSIBLE
A – INSTRUCTOR’S NOTES
Aim
1. To teach the method of laying a fixed line by night when it has not been possible to make preparations in daylight.
Class and instructors
2. One officer instructor and not more than 30 in the class.
Periods
3. One 45-minute lecture.
Stores
4. No stores required.
B – CONDUCT OF LESSONApproach
5. Give the aim of the lesson (see para 1 above).
6. State that it may sometimes be required to lay a fixed line to protect a locality by night when no daylight reconnaissance or preparation has been possible. Such an occasion might arise after a night attack when machine guns are required to assist in re-organization. This may be carred out by either of the following methods dependent on the circumstances:-
Method 1
When no safety is involved and a light can be shown from the place at which the fire is required to fall, the following procedure will be adopted:-
- (a) Shine a light from the area in which the fixed line is to fall.
- (b) Obtain the range to the light by rangefinder.
- (c) Lay the guns on the light, using the tangent sight set at the range obtained.
- (d) Record the QE, and the angle between the line of fire and the aiming lamp and continue as in Lesson 105.
Method 2
When flanking safety is involved and a line can be shown from the front edge of the defended locality to be protected, then the following method can be adopted:-
- (a) Shine a light from the front edge of the locality.
- (b) Obtain the range to the light by rangefinder.
- (c) Using the tangent sight set at the range obtained, lay the guns on the light.
- (d) Set the deflection drums of the dial sights at the safety allowance and tap the guns until the lensatic sights are laid on the light.
- (e) Record the QE.
- (f) Set the dials of the tripods at zero. Put out the aiming lamp and, using the deflection drums, align the lensatic sight on it.
- (g) Note the elevation and the angle measured. Half load and press the thumb-piece.
NOTE:- This method must NOT be used for OVERHEAD fire.
Conclusion
7. Questions to and from the class.
8. Sum up main points.
9. This lesson is best practised during section training at night.
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