Instead of croaking an enemy, a Unit can attempt to capture it. A Unit that is captured is in the possession of the capturing Side.
A captured Unit takes Turn with the Side that captured it.WoT-2786759 A Unit's upkeep is paid by the capturing Side, and so the food tends to be lower quality.
This is generally used for casters, who are rare and valuable, and not warlords, whose duty and loyalty make them unlikely to join their captors. It is unknown if basic troops can be captured.
Proposed Spec: Jillian has been captured by Gobwin Knob forces many times, only to "escape" each time.
Proposed Spec: Charlie offered to capture Parson and later made Ansom agree to only capture, and not croak, him.
Speculation: Jack Snipe joined Stanley after he destroyed Faq, and was captured.