Assault is the wrong term, Nyjer committed simple battery.
At common law, simple battery is a misdemeanor. The prosecutor must prove all three elements beyond a reasonable doubt:
an unlawful application of force
to the person of another
resulting in either bodily injury or an offensive touching.
Simple battery may include any form of non-consensual harmful or insulting contact, regardless of the injury caused. Criminal battery requires an intent to inflict an injury on another, as distinguished from a tortious battery.