Quote Originally Posted by Dol Guldur
Does anyone know how to get a timed reinforcement army in an historical battle to appear and come under the control of a playable army?

I cannot work out what supporting_armies does yet, maybe it is connected to that...

Any help is appreciated.
Unfortunately I have not the answer, but only two remarks that might help you.

We have used in ITW two functions that combined might allow the player to control the reinforcements.

First: some reinforcements can be included in battle. But we have used this feature with armies different from the playable one.
Example:
Code:
reinforcement	numidia, 0, no_withdraw, supporting_armies 0
reinforcement_time	0.011

deployment_area_point	509.002, 282.083
deployment_area_point	424.908, 733.092
deployment_area_point	291.596, 716.587
deployment_area_point	326.570, 314.146

unit			0, 390.384, 676.590, 176, formation_type square, formation_width 117.859
unit			1, 406.503, 696.447, 174, formation_type square, formation_width 96.878
unit			2, 341.895, 356.209, 19, formation_type square, formation_width 287.193
unit			3, 334.070, 336.052, 19, formation_type square, formation_width 238.710
The first possibility would be to put a second army of the same faction as the human player faction and try to see if it is playable.

Second: you can deploy the same army in two different places of battlefield.
Example:
Code:
army	romans_julii, 0, no_withdraw, supporting_armies 0

deployment_area_point	211.806, 594.831
deployment_area_point	441.631, 604.272
deployment_area_point	438.889, 389.637

unit			0, 421.821, 487.511, 93, formation_type square, formation_width 8.972
unit			1, 394.574, 487.929, 92, formation_type square, formation_width 8.613
unit			2, 427.642, 468.474, 96, formation_type square, formation_width 21.973
unit			3, 374.356, 509.923, 100, formation_type square, formation_width 10.800
unit			4, 379.645, 530.966, 96, formation_type square, formation_width 13.316
unit			5, 368.756, 494.596, 101, formation_type square, formation_width 16.968
unit			7, 349.020, 538.322, 95, formation_type square, formation_width 45.531
unit			9, 297.835, 589.372, 92, formation_type square, formation_width 13.228
unit			8, 343.080, 584.770, 94, formation_type square, formation_width 44.260
unit			10, 297.753, 576.128, 91, formation_type square, formation_width 13.454
unit			11, 297.608, 561.676, 91, formation_type square, formation_width 13.035
unit			12, 297.405, 546.368, 90, formation_type square, formation_width 5.485

deployment_area_point	460.680, 351.343
deployment_area_point	116.183, 489.016
deployment_area_point	116.813, 596.999
deployment_area_point	450.600, 621.637

unit			13, 204.470, 508.626, 64, formation_type square, formation_width 4.215
unit			14, 232.996, 561.339, 68, formation_type square, formation_width 20.975
unit			15, 244.599, 537.587, 66, formation_type square, formation_width 1.000
unit			16, 205.552, 527.030, 69, formation_type square, formation_width 13.833
unit			17, 199.517, 541.458, 67, formation_type square, formation_width 13.463
unit			18, 194.478, 559.026, 65, formation_type square, formation_width 12.087
unit			6, 154.503, 510.580, 66, formation_type square, formation_width 12.479
unit			19, 146.136, 526.873, 67, formation_type square, formation_width 13.147
The second possibility is: what would happen if the second part of the army is placed outside of battlefield? (I mean outside the red line). Would it be considered as a reinforcement?
In case this army cannot be moved, a script would be needed to move it to a zone inside the red line.

I hope this helps.