Chains of the Sea

One day the aliens landed, just as everyone always said they would.
They fell out of a guileless blue sky and into the middle of a clear, cold
November day, four of them, four alien ships drifting down like the snow that
had been threatening to fall all week. America was just shouldering its way
into daylight as they made planetfall, so they landed there: one in the
Delaware Valley about fifteen miles north of Philadelphia, one in Ohio, one in
a desolate region of Colorado, and one -- for whatever reason -- in a cane
field outside of Caracas, Venezuela...