"It may be doubted whether so small a number of men ever employed so short a space of time with greater or more lasting effects upon the history of the world.” — Sir George Otto Trevelyan on the Battles of Trenton and Princeton
In my opinion it is just ONE attempt.
That is correct; the rule is NOT that one stack/unit may intercept. It is that one ATTEMPT to intercept may be made.
However, one attempt may be made for EACH space entered by the active stack.