ABSTRACT
LONDON owes much of its size and power to its commanding position astride the Thames. Mackinder remarked that London Bridge is the pith and cause of London. I The river is navigable for sea-going vessels as far as London, but not much higher. Hence London became a point of trans-shipment from water to land, and from river to sea. Downstream, the river would in past centuries have been impossible to bridge owing to its great width, and dangerous to ford on account of the heavy tides and broad marshes. The estuary is well placed for ships voyaging to and from the continent. London cannot be attacked or captured from the sea alone, although it could be defended almost entirely by seapower in the days before aviation. There are no physical obstacles to development until one reaches the Chiltem Hills in Hertfordshire or the North Downs in Surrey and Kent.
