A formation which very often occurs in the middle game is the so-called “elbow.”  It consists of three men arranged like the white pieces in Diagram 108.

32        31        30
+---------------------------------------+
|    |    |    |    |    |    |    |    | 29
|---------------------------------------|
28 |    |    | o  |    |    |    |    |    |
|---------------------------------------|
|    |    |    | o  |    |    |    |    | 21
|---------------------------------------|
20 | *  |    |  o |    |    |    |    |    |
|---------------------------------------|
|    |  * |    |    |    |    |    |    | 13
|---------------------------------------|
12 | *  |    |    |    |    |    |    |    |
|---------------------------------------|
|    |    |    |    |    |    |    |    | 5
|---------------------------------------|
4 |    |    |    |    |    |    |    |    |
+---------------------------------------+
3         2        1

Diagram 108.

When adequately supported an elbow forms a solid position which cannot easily be attacked.  An example of a strong elbow will be found in the following game: 

32        31        30
+---------------------------------------+
|    |  o |    |    |    |  o |    |    | 29
|---------------------------------------|
28 |    |    |    |    |  o |    |    |    |
|---------------------------------------|
|    |    |    |    |    |    |    |  o | 21
|---------------------------------------|
20 |    |    |  o |    |    |    |  o |    |
|---------------------------------------|
|    |    |    |    |    |  * |    |  o | 13
|---------------------------------------|
12 |  * |    |  * |    |  * |    |    |    |
|---------------------------------------|
|    |    |    |  * |    |  * |    |    | 5
|---------------------------------------|
4 |    |    |    |    | *  |    |    |    |
+---------------------------------------+
3         2        1

Diagram 109.

          Black White

(1) 10-15           23-19
(2) 6-10            22-17
(3) 1-6             25-22
(4) 11-16           17-13
(5) 16-23           26-19
(6) 7-11            29-25
(7) 11-16           22-17
(8) 16-23           27-11
(9) 8-15            24-19
(10) 15-24           28-19
(11) 4-8             25-22
(12) 8-11            31-26
(13) 3-7             22-18
(14) 9-14            18-9
(15) 5-14

The men on 6, 10, 13, 14, 17 and 21 form the elbow, the strength of which becomes apparent on the 19th move.

(15) ... 26-23 (16) 11-15 32-28 (17) 15-24 28-19 (18) 7-11 30-26 (19) 2-7 19-16 (20) 12-19 23-16 (21) 11-20 26-23 (22) 7-11 and wins.

The danger involved in an elbow, which is not sufficiently backed up, is shown in the following game.

Black White