Aerial photograph of Pearl Harbor before the attack
U.S. Navy

Ports are where land meets sea. They are installations equipped to dock ships, load and unload their cargoes, provide logistical services, and shelter ships from storms. The U.S. Navy raised units called Cubs and Lions to organize naval bases at ports: A Cub was capable of developing a medium-sized forward naval base, while a Lion was capable of developing a major naval base.

A modern port included:

Docks. Ships in port could not load or unload efficiently except at docks, where a landing was built next to water deep enough to accommodate the ship. A modern dock was equipped with cranes and rail spurs to allow the ship to be loaded or unloaded directly to a rail car for transport inland. In the absence of docks, as at Guadalcanal early in the war, ships had to be unloaded by lighter (small boats or landing craft), which was a slow and manpower-intensive process.

A rough rule of thumb was that a single berth could load or unload six ships per month.

Seagoing ships usually required the assistance of tugs to help them through the channel connecting the docks to the open sea.

Anchorages. It was useful, particularly for naval bases, to have a sizable anchorage for ships sheltering from storms or otherwise not in need of actual dock space.

Breakwaters. Ships in port needed protection from wind and waves. Natural harbors such as San Francisco Bay were almost completely surrounded by land that provided such protection. Such harbors are uncommon, and artificial harbors such as Colombo or Los Angeles had man made breakwaters. A port with little natural protection is referred to as a road stead.

Logistics. Ships require fuel oil and other provisions to operate. Modern ports had tank farms and refueling facilities adequate to support the traffic through the port. These were vulnerable to attack, and Nagumo has been heavily criticized for failing to destroy the tank farms surrounding Pearl Harbor during the attack of 7 December 1941 that marked the outbreak of war. Warships also require ammunition dumps from which to replenish their magazines. The United States attempted with considerable success to substitute for modern port facilities with an extensive fleet train of oilers, provisions ships, ammunition ships, and other supply ships that could resupply fleets at advance bases or even on the high seas. Japan also made use of underway replenishment, particularly refueling at sea, but not nearly as successfully as the Americans. However, the fleet train ultimately had to extend back to a modern port with the necessary logistical facilities.

The Americans rapidly expanded logistical facilities at major ports they intended to keep after the war, such as Pearl Harbor and Guam. At other advanced bases, such as Ulithi, the Americans used obsolete tankers, each with a capacity of 60,000 to 80,000 barrels (8000 to 11,000 tons), to serve as floating tank farms.

Defense. Ships in port are unable to maneuver, which is one of their best defenses against bombing or torpedo attack, and important ports were equipped with abundant antiaircraft and with torpedo nets to foil torpedo attack. The nets were opened or closed as required by small net tenders. In addition, the port might be protected by minefields. Important ports invariably  had airfields basing fighters nearby as well as the best radar available.

Maintenance. Ships require repairs and maintenance, and modern ports had extensive machine shops to perform the necessary work.


Morison (1958)

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