Fighting without expectation of victory

In re-reading The Lord of the Rings, I have been struck by the determination of the Fellowship (particularly Frodo) to press on without any reason to believe in the final success of the mission.  F. Scott Fitzgerald had something to say about that:
The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.
One should, for example, be able to see that things are hopeless and yet be determined to make them otherwise.
F. Scott Fitzgerald, “Pasting It Together,” Esquire, March 1936.

It is a nearly necessary characteristic for the criminal defense attorney as well — many, of course, have been driven to drink, instead.