The technique that W.E. Fairbairn called the Thumb Hold was one that for a long time puzzled me. I could see that it was an effective prisoner control technique. Fairbairn would not have recommended it unless this was so. The principle of final lock was easy enough to understand. The problem was how did you get to this final destination?
The key to grasping this technique (pun intended) is to study Fig 44 below. Note how your hand comes up from the knife edge part of the hand, passes across the back of the hand and secures the thumb with the fingers while your thumb slips between his.
Although Chinese martial arts were seldom taught to non-Chinese in the early 20th century there does seem to be some evidence that Fairbairn had some instruction in some Chinese techniques. The Thumb hold may be the Chin-na technique called Yu Wo Tong Xing or, in English, Walk With Me.
Below is a reproduction of the relevant illustration from Fairbairn's book. I have coloured the figures in the hope that it makes the technique a little clearer. I have also taken the liberty of flipping the illustrations to show them applied against the victim's right arm rather than his left. If you are a Police officer you probably carry your firearm on your right side so it is better to apply this technique so your weapon is furthest from your prisoner. The prisoner will probably be right handed so immobilizing his right arm may hinder him using any concealed weapons you may not have been aware of. Appling the technique using your left keeps your right hand free to use your firearm should there be trouble from a third party. There are therefore sound reasons for preferring to apply this technique against the suspect's right arm whenever possible and the rest of the page will be written assuming this is your intention.
Thumb hold is a mirror move, by which I mean you apply it right hand against his left, or in this case your left against his right.
Hook or thrust your left thumb up into the web of his hand between his fingers and thumb. The Tip to remember how this goes is to turn your left hand palm up as though asking for a tip. Fig 42 is not that clear but I believe is supposed to show the action viewed from the German's right side.
What you are going to do now is make two circular movements. With your right foot step back and make a reverse 180 degree turn so you face the same direction as your prisoner. At the same time you move your linked hands in a vertical circle across the prisoner's front. Your hands start off low, circle up over to the prisoner's left then come down back on his right side to finish as shown in Fig. 44. As you made your backward turn and vertical circle you let your left arm slip behind his right so it ends up between his arm and body as shown.
Your right arm helps get his right arm circling by patting his elbow and acting as a fulcrum. This is shown in Fig 43, which is possibly the most confusing illustration in this sequence. I believe it is supposed to show a view of the German's arm viewed from the thumb side. The German's thumb is pointing downwards concealed by the Tommy's hand. The Tommy is in the process of making his rearward turn, bringing back his right foot and pivoting on this left and is about to use this motion to rotate the German's elbow. Fig 44 is viewed from the same angle but the Tommy has turned to face in the same direction. Note that his thumb will be positioned on the same as you.
Fig. 45 is notable in that it shows the Tommy stabilizing the German using his other hand while using the thumb hold to bring the prisoner up onto his toes and keep the German slightly out of balance. Using the German's thumb as a lever he can both bend and twist the wrist joint by just moving his hand towards himself and can also control the elbow.
The Thumb hold in Fairbairn's own words, directions adjusted for application against the right arm:-
Stand facing your opponent and slightly to his right. 1. Insert your left thumb between the thumb and forefinger of his right hand, your fingers under the palm of his hand, your thumb to the left (Fig. 42). 2. Seize his right elbow with your right hand, knuckles to the left, and thumb outside and close to your own forefingers (Fig. 43). 3. Step in towards your opponent; at the same time, turn your body so that you are facing in the same direction, simultaneously forcing his right forearm up across his chest and towards his right shoulder by pulling his elbow with your right hand over your left forearm and forcing upwards with your left hand (Fig. 44). 4. Release the hold with your right hand just as soon as you have pulled his elbow over your left forearm, and hold your opponent's right elbow very close to your body. 5. Keeping a firm grip on the upper part of his right arm with your left arm, immediately seize the fingers of his right hand with your right. This will prevent him from trying to seize one of the fingers of your left hand and also give you an extra leverage for applying pressure as follows: 6. Press down on the back of his hand towards your right-hand side with your left hand. Should your opponent be a very-powerful man and try to resist, a little extra pressure applied by pulling his fingers downwards towards your right-hand side with your right hand will be sufficient to bring him up on his toes and convince him that he has met his master (Fig. 45).
Rex Applegate's book Kill or Get Killed contained many of the techniques Fairbairn taught and the following photos are reproduced from that source. Again, I have flipped the images to show application against the right arm.
The left image gives us a much better view of the process Fig.43 was supposed to show. We can see the arm is about to be rotated about the elbow vertically and that the lower arm will be slipped between the arm and body as the Soldier applying the technique moves closer to the camera and turns to face towards our right. This picture actually shows the application of a wrist hold. The wrist hold is a related technique to the thumb hold and is applied with the same action. The difference is for the initial grip the palm of your left hand is placed on the back of his right hand, your thumb over the little finger side of his right hand. Note that in this example the thumb points in the same direction as the fingertips. Stepping back and circling the arm places the prisoner in the bent wrist and elbow position and pressure can be applied by moving his hand towards oneself. In some versions of his book Applegate observes that under certain conditions taking hold of the whole hand to apply the wrist hold may be more easily achieved than trying to initially slip your thumb between his thumb and finger. His suggestion is to apply the wrist hold then use your free hand to secure the prisoner's wrist while you shift your other hand to hold the thumb.
Crude and Rude. This is an alternate method for applying the technique that will not win you any points for elegance, but may be simpler to achieve in the heat of action. Grab the prisoner's right wrist with your left hand. Execute the backstep and hand circling action. As you circle the hand you will probably have trouble maintaining the wrist grip, so as soon as possible also take hold of the wrist with your right hand. Slide your left hand across the back of his right hand and hook the thumb to apply the Thumb hold.
OR Apply a basic wristlock with either hand. Grasp the side of the hand and push into the back of the hand with your thumb to bend the wrist forward. Apply your other hand to the wrist lock for more control.
Maintain pressure on the opponent's wrist with your right hand, step forward, and pivot around to stand next to the opponent.
Release your left hand, quickly reach under the opponent's right arm from behind, and grab his hand.
Use the left hand and apply downward pressure on the opponent's wrist. Or secure his thumb to press down and rotate the wrist joint.
Thumb hold applied from the Rear Quarter.
Slip your left hand between his upper arm and body to grip the biceps. At the same time take his right wrist in your right hand. Turn your right hip in to bend the elbow joint and then turn to your right to slip behind, converting the force into a pull. Slide your left hand from his biceps across the back of his right hand and hook his thumb.
Another variation of the basic technique taken from this page. In this case White applies a wrist hold, clamps the right arm with his left and employs pressure with his right. Pull the hand toward you to exercise control. This could easily be converted into a thumb hold with the left. He does not attempt to bend the elbow until he is beside the prisoner. The position of Black's hand would have made it difficult to have applied the thumb grip from the start. Also note that White has made his initial grip to the little finger side of the hand but with his thumb pointing in the opposite direction to Black's fingertips. This sequence might also suggest what could be done if you initially made a same hand grip, using your right hand against his right.
Tactical Analysis. Fairbairn sums up the pros and cons of the Thumb hold very nicely:-
This is the most effective hold known, and very little exertion on your part (three to four pounds' pressure) is required to make even the most powerful prisoner obey you. It is possible also for you to conduct him, even if resisting, as far as he is able to walk. You have such complete control of him that you can, if necessary, use him as cover against attack from others. The movements you have to make to secure this hold are very complicated, which is mainly the reason why it is almost unknown outside of the Far East. But the advantage one gains in knowing that he can effectively apply this hold more than repays for the time that must be spent in mastering it. First concentrate on making every move slowly, gradually speeding up until all movements become one continuous motion. When you have thoroughly mastered the hold, then learn to secure it from any position in which you have secured your opponent. It should be understood that this hold is not a method of attack, but simply a "mastering hold," which is applied only after you have partially disabled or brought your opponent to a submissive frame of mind by one of the follow up methods
I would not bother to teach the Thumb hold in a general self-defence course. It is too intricate and serves little defensive purpose. For Police and Prison officers it is a useful technique to be proficient in, however. At least a day should be spent practising the Thumb hold and its related variations. Suggested topics would be:-
Application of the Thumb hold to either the left or right arm.
Application of the wrist hold to either the left or right arm.
Alternate ways to apply the hold.
Application of hold against suspects in varying positions such as seated, sitting on the floor and so forth.
Converting a same hand hold into a Thumb hold.
Applying the hold from differing angles and directions.
Converting other holding techniques into a Thumb hold.
Dealing with counter attacks and resistance from held suspects.