He had sent three scouts to Commodore Stockton at San Diego, asking for immediate help, but the three were captured by the Mexicans on their return.

Kearney had succeeded in exchanging a Mexican lieutenant, whom he held prisoner, for one of the scouts, but nothing was gained thereby.

The messenger reported that they had been unable to reach San Diego, and Commodore Stockton, therefore, was in ignorance of the peril of his countrymen not far distant.
When every one expressed himself as unable to see the first ray of hope, Carson in his deliberate, modest way said that it was clear only a single possibility remained--that was by procuring relief from Commodore Stockton at San Diego.

Though the other scouts had failed to reach him, Carson expressed his belief that he could succeed.

At any rate, he desired to make the attempt to pass the Mexican lines.
Lieutenant Beale, since Minister to Austria, and favorably known throughout the country, immediately seconded the proposition, volunteering to accompany Carson.