Field artillery contributes to unified land operations by massing fire with precision on targets.

The concept of massing fire is crucial to the effectiveness of field artillery in unified land operations. This involves concentrating artillery firepower at a specific location to achieve a greater impact on the enemy. By massing fire, units can deliver a high volume of ordnance onto a designated target area, which often leads to increased destruction of enemy forces, equipment, or fortifications with improved accuracy.

This capability allows field artillery to support maneuvering forces effectively and plays a vital role in shaping the battlefield. Units that can efficiently mass fire provide a tactical advantage by overwhelming the enemy's defenses and diminishing their ability to operate.

In the context of the other choices, placing indirect fire refers to the method of targeting that utilizes indirect firepower rather than direct line of sight. Denying the enemy typically involves strategies to limit or counteract their access to certain areas or resources. Converging fires involves multiple units targeting the same area but doesn’t emphasize the specific concentration of artillery fire as massing fire does. Each of these concepts plays a role in military operations, but massing fire is particularly impactful for maximizing the effectiveness of field artillery in unified land operations.