Definition of "truculently"

Truculently they squared up to each other but kept just out of fighting distance?

1954, William Golding, “chapter 11”, in Lord of the Flies

It was a casual sneer, obviously one of a long line. There was hatred behind it, but of a quiet, chronic type, nothing new or unduly virulent, and he was taken aback by the flicker of amazed incredulity that passed over the younger man's ravaged face. Toberman was disconcerted. ‘What's the matter?’ he demanded truculently.

1963, Margery Allingham, chapter 8, in The China Governess: A Mystery, London: Chatto & Windus

`What's wrong with that?' he demanded truculently.

1965, James Holledge, What Makes a Call Girl?, London: Horwitz Publications, page 128