When he reached the new world, Cortez burned his ships. As a result, his men were well motivated.

7 seconds sound clip from the The Hunt for Red October movie soundboard.

You can hear this line at 00:47:36.133 in the Blu-ray version of the movie.

Quote context

[...]

- Everything that happens on this ship affects us all.

- The master-at-arms is already suspicious.

- We could still go back.

- There will be no going back.

- Before we sailed, I dispatched a letter to Admiral Padorin, in which I announced our intention to defect.

- In the name of God, why?

- When he reached the new world, Cortez burned his ships. As a result, his men were well motivated.

- You have signed our death warrants.

- Padorin will send the entire fleet.

- Jesus, they'll find us.

- They'll find us and hunt us down. No one's going to find us. That's enough, Yuri.

- You had to do it, huh? You couldn't just turn the submarine over to the Americans. You had to make a political statement.

[...]