What term refers to a situation where troops are positioned and require support from artillery?

The term "troops dug-in" accurately describes a situation where soldiers are in fortified positions, typically with the intention of holding their ground while awaiting further instructions or support. In military operations, being "dug-in" implies that troops are not only positioned to resist enemy actions but are also in a prepared state for potential engagements. This situation often leads to a request for artillery support to enhance their defensive capabilities or to provide cover as they execute their mission.

In the context of the other options, "troops in contact" refers to forces currently engaged with the enemy but doesn't necessarily indicate a requirement for artillery support. "Support by fire" is a tactic where one unit provides covering fire for another unit’s movement but does not define a condition where troops are specifically in need of artillery assistance. "Close support" generally entails immediate fire support provided to maneuvering units but does not specifically denote a state of readiness or need for support by artillery like being dug-in does. Thus, "troops dug-in" conveys a clearer idea of an established position, highlighting the necessity for artillery support in such scenarios.