Some kind of a survey had already been made supporting the idea that a railway could be built from San Mateo to the shores of Half Moon Bay. Assuming this iron road was constructed (which it wasn’t) experts said the railroad would be one of the first things the enemy would take control of.
If they commandeered the railroad, and somehow cut-off communications with the rest of the Peninsula, the enemy (hypothetically) could have the wealth of the Santa Clara Valley at their feet–they could even establish headquarters at San Jose “and live off the fat of the land.”
When a Southern Pacific Railroad official was asked to estimate how many men the train could move in 24 hours from San Francisco to San Mateo, he said using two trains with 12 cars each and 72 men in each car— 1680 men could be moved in one hour; 320 in 24 hours.
All of this led observers to believe that if an enemy landed at Half Moon Bay, unobserved, he could disembark an army, cross the country to the railroad line, and seize it before any counter force was gathered to oppose him.