The Roman general did the same, induced by necessity, rather than by the favourableness of the occasion.
Cited from The History of Rome; Vol III, Books 27 to 36, by Titus Livius
It is by the favourableness or otherwise (of time and place) that the opportuneness of an act is determined.
Cited from The Mahabharata of Krishna-Dwaipayana Vyasa, Volume 2
Three situational components determine the favourableness of situational control: When there is a good leader-member relation, a highly structured task, and high leader position power, the situation is considered a "favorable situation."
In his 1976 book Improving Leadership Effectiveness: The Leader Match Concept, Fiedler (with Martin Chemers and Linda Mahar) offers a self paced leadership training programme designed to help leaders alter the favourableness of the situation, or situational control.