Located in today's country of Columbia, the city was encircled by a broad creek, which ran round it from the inner harbor to the sea in such a way as to form a wide natural moat, rendering the city unapproachable from the mainland except by a bridge. This bridge was also commanded by the harbor fort, nor were land operations possible at any other point except from that part of the spit which lay between the city and the Bocca Grande. So finely, however, did this narrow down before the city could be reached, that between the inner harbor and the sea it was but fifty paces wide, and here the Spaniards had had time to prepare defenses that looked impregnable. From shore to shore a formidable entrenchment completely barred the way; and not only was its front so staked and encumbered as to render a night attack impossible, but its approaches were swept by the guns and small-arms of a great galeas and two galleys which lay in the inner harbor.
For more on Drake's opening moves here is an installment from Drake Captures Cartegena; Raids Cadiz by Julian Corbett: http://dld.bz/fc9v2
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