Why did Cortes scuttle his ships?

Answer 1

Cortes and his 500 soldiers were stationed in Vera Cruz, he wanted to march forward towards Tenochtitlan. But there was a part of his force that thought the idea was suicide and preferred to return to their base in Cuba and return with more men. Rumors started of a possible mutiny, and of soldiers sneaking off with ships. Cortes could not afford to lose any of his men or ships.

So the idea came about to sink 10 of the 11 ships. He did this with a few men in secret, at first he claimed the first 4 or 5 boats sank naturally. But when the other boats sank the men became furious, blaming Cortes for certain death in Mexico.

Cortes laid out one of his Famous Speeches at this point. Telling the men that what awaits them in Tenochtitlan are riches, and that to embark on such a perilous journey with one eye always looking back at the ships would doom it to failure. He said for all you who are truly afraid there is still one boat left. We will provision it and allow anyone to return to Cuba who desires to do so. When we return from Mexico with riches we will fill you in on the stories of adventure and glory... After this speech, not one man left.

Although he sank the boats, he was wise enough to save the sails and ropes. These were later critical for use on the brigatines that he ordered built for the final siege of Tenochtitlan.