Instructions for laying minefields

The instructions below are taken from a 1941 defence scheme and make interesting reading. One or two paragraphs have been omitted, but the text is otherwise as originally written. The minefield spacing and layout diagrams have been based on originals that accompanied the instructions. An interesting point not made below is that all minefield warning signs were to be removed upon "action stations" being given.

Instructions for laying mushrooms

1. Responsibility

1. The siting of minefields is the responsibility of Sector Commanders, subject to Divisional Commander's final approval.
2. The fencing, signboards, laying and charting of minefields is a Royal Engineers responsibility. Sector Commanders will be asked to provide working parties for wiring etc.

2. Siting

The Field Company commander in collaboration with the sector commander will give technical advice and bear in mind:

(a) Extent of minefields

The minimum spacing is 21 feet between mines. Sympathetic detonation may take place, so to localise risk, no minefield will be larger than 1200 feet without a gap. Where depth is available a staggered field behind the gap is to be employed. The distance to be left clear between such fields will be a minimum of 90 feet and 60 feet. The mines will always be laid in regular rows.

(b) Distance from occupied buildings

No minefield may be sited so that a mine is nearer than 450 feet to a building occupied by civilians. The term "building" includes such places as railway stations and signal boxes. If it is essential to site the field nearer than this the civilians must be evacuated.

(c) Storm water mark

No mines are to be laid below "storm high water mark" of the most exceptional tide combined with heavy seas. Local advice will be obtained.

(d) Sea Walls

Mines will never be laid on or against the sea wall, as one mine may do serious damage with resultant flooding.

3. Perimeter fences

Every minefield will be surrounded by a barbed wire obstacle, either double apron or triple Dannert fence. It must be firmly fixed to the ground to the satisfaction of the local RE Commander.

The trace of the perimeter fence should show an irregular pattern to air photography and as far as possible be incorporated with other barbed wire obstacles.To achieve this it is obviously impossible to site the perimeter fence close to the edge of minor roads throughout. Deception is so important, larger traces and the enclosure of unnecessary ground in the field will often be justified in view of the very great importance of misleading the enemy, primarily in the air but also on the ground.

4. Signboards

Danger notices will be erected around the perimeter of every minefield:

1. On the home side facing home troops
2. On the flanks facing at an angle such that they can be read from the front but not from the enemy side.

They will be made 1 ft high by 1.5 ft wide painted white and having in bold red letters "DANGER MINES". Each board will be securely tied to a post about 4 ft above the ground and the post is to be stayed to prevent being blown down.

5. Procedure for laying

The exact siting of the minefield, spacing and number of rows having been decided and approved, the following sequence of work will be adhered to:

First stage

(a) The perimeter barbed wire fence will be erected around the field. A small gap or gaps will be left open to allow the passage of men working in the field. At every gap will be placed the necessary wire etc, to close it.

The RE officer in charge of the work will be responsible that:

1. Each gap is permanently closed as soon as its utility ceases.
2. All gaps are closed before men break off work for any reason.
3. All gaps are finally and permanently closed as soon as the minefield is completed.

(b) The signboards will be erected.

(c) The main recovery posts, main recovery wires and marking pegs for the whole field will be fixed.

(d) The position of every mine will be indicated by a peg inserted about 3 inches clear of where the safety handle of the mine will eventually be placed.

(e) RE personnel will examine and test each mine as follows:

1. Make certain that the primer case is not in the mines.
2. Slip off the rubber cover and examine for slits or cuts. If defective the whole mine will be put aside and not used.
3. Test the top plate to ensure that the centre bolt is not too tight. The plate should revolve easily in the outer ring and should show a slight play when rocked. If it does not do so, loosen the top nut, slack off the centre bolt until the plate revolves freely and then tighten the nut again. After tightening the nut, test the plate again.
4. Ensure that there is plenty of grease on the safety handle where it slides into the case. Work it in and out to see that it works easily.
5. Replace the rubber cover.
6. MAKE CERTAIN THAT THE SAFETY HANDLE IS IN THE "SAFE" POSITION. Mines will be laid on the same day, otherwise they will be re-examined the following day.

Second stage

The Officer and NCO in charge of the work will decide what area of the minefield can be laid complete (except for arming) before cessation of the day's work. The portion to be completed during the day's work will be divided from the remainder into some very conspicuous manner e.g. white tapes and pegs. Once the decision has been made and the demarcation tape laid, only the minimum number of men needed to lay and prime the mines will be allowed to enter the minefields.

He may then go on to other work and leave the NCO in charge who will organise the men to work in pairs and carry out the following operations in sequence:

1. Carry up mines and lay close to their respective pegs in the minefields.
2. Securely fix the recovery wires to the mines.
3. Dig a hole for each mine so that the top of the mine is not more than 2 inches below ground level.
4. MAKE CERTAIN THAT THE SAFETY HANDLE IS AT THE "IN" (SAFE) POSITION.
5. Insert the primer assembly ensuring that it is pushed well home before the bung nut tightens up. The NCO will inspect each mine on completion of this operation.
6. Place mine in its hole. Mines will be so placed that all safety handles throughout the minefield point in the same direction away from the enemy.
7. Bed mine well down, ensuring that no pressure of any sort is brought on the cover during the operations. Fill in the hole round the mine with soil and shingle and cover the top of the mine with not more than 2 inches of soil, shingle or sod to conform with surroundings. A small hole around the safety handle will be left open and free of soil.
8. Attach the branch recovery wire to the main recovery wire having formed a nut in the branch wire three feet from the mine.
9. Remove any surplus spoil in a sandbag.

(c) The above work will be co-ordinated so that pairs of men work on the rows of mines (leapfrogging each other if necessary) from one end of the field towards the tape indicating the limit of the day's work period.

The NCO in charge will inspect each mine to see that it is properly laid, the branch recovery wires attached and fixed and spare spoil removed. As men complete their mine laying they will be withdrawn outside the perimeter fence.The pegs marking the position of each mine will NOT be removed at this stage.

(d) If the minefield is not completed within one day, the above procedure of laying mines will be followed on the subsequent day or days until the whole minefield is laid.

(e) Where the minefield takes more than one day to lay, the demarcation tape will be left in position over night. No man will be allowed to cross the tape on to the portion of the minefield already laid without a definite order from the RE officer in charge.

(f) No portion of the minefield will be armed until the WHOLE field is laid.

(g) Holes dug from mines are visible in an air photograph and if the number are dug and left, they will show not only the position but also the spacing of the minefield. The digging of each hole, the insertion of the mine and the covering up and disposal of surplus spoil will therefore be completed as one operation in the case of each mine.

Third stage

The minefield being completely laid, the officer in charge will order all personnel out of the field and close all entrances except one. The minefield will then be armed by a selected RE NCO or Sapper under the supervision of the RE Officer. The work of arming will be carried out progressively through the field finishing at the gap which has been left open. The progress of arming will be so arranged that a man arming the mines never returns over the mines he has already armed. The arming tool will always be used.

THE GREATEST CARE WILL BE TAKEN TO ENSURE THAT THE TOP OF THE MINE IS NOT TOUCHED.

After each mine is armed the cavity in the ground round the handle will be lightly filled with soil and the marking pegs pulled up and placed in a sandbag. On completion of work these pegs will be counted to check the number of mines in the field and that all mines have been armed.

When arming has been completed the remaining gap in the perimeter fence will finally be closed. Thereafter no individual will enter the minefield without prior authority from the Divisional Commander. Completion of the minefields will be reported to the local commander, Brigade commander and the CRE.

6. Charting of minefields

(a) The Field Company Commander in whose sector a minefield is to be laid will be responsible for recording accurately the extent of the perimeter wire, the layout of the mine, main recovery posts and wires. This will be drawn to a scale of 30 feet to 1 inch and be marked in addition on the 1 mile to 6 inch map provided for the purpose.

(b) Accurate bearings will be taken from the main recovery posts onto prominent features to ensure that if damage takes place (by bombing or similar enemy action) the post can be fixed.

(c) The charting will be prepared as the work is proceeding and be completed before the minefield is armed.