He was accused of 'assault'. = He was charged with 'assault'. = 'Assault' charges were brought against him.
He came 'under assault' for his unusual beliefs. [=he was severely criticized for his unusual beliefs]
He was found guilty of 'sexual assault'. [=the crime of touching someone in an unwanted sexual way]
(..) You know of what I speak,Gandalf. A Great Eye,lidless,wreathed in flame. The Eye of Sauron. He is gathering all evil to him. Very soon,he'll have summoned an army...great enough for an assault upon Middle-earth. You know this? How? I have seen it. A palantir is a dangerous too,Saruman. Why? (..)2001 The Lord of the Rings: The Fellowship of the Ring