Final answer:
Speed is the greatest asset of a strike force in military tactics, as it enables rapid engagement and tactical adaptability. In historical examples, the Union's strengths did not include defensive fighting while the Confederacy lacked a strong navy. Force is described by dynamics in physics, not by kinematics.
Step-by-step explanation:
Among the characteristics of a strike force—speed, size, visibility, and predictability—the greatest asset in military tactics is speed.
A rapid and swift strike force can engage and disengage from combat situations effectively, allowing for surprise attacks and quick adaptations to changes on the battlefield. This contrasts with the importance of size, which can be a disadvantage if the force is too large to mobilize quickly; visibility, which could make a force more susceptible to being targeted; and predictability, which would negate any element of surprise.
In historical context, during the American Civil War, the Union had several advantages, but the ability to fight defensively rather than offensively was not considered one of them. Conversely, the Confederacy lacked a strong navy, making it their disadvantage. In the realm of physics, force is a physical quantity described by dynamics, setting it apart from kinematics which solely deals with motion without considering its causes.