Tinuviel's Tears wrote:
Do you mean, how could he have gone into a hopeless battle like that, knowing he was going to lose?
I think that's what he means.
Frodo and Sam would have never made it through Mordor had there not been a distraction. Aragorn and Gandalf both knew this, and they knew what must be done. Aragorn also knew that if they all died, they would die knowing that Frodo had made it to Mordor with their help. There really wasn't any other way. It was them or Frodo.