The primary modern meaning for sally port
is a secure, controlled entryway, as at a fortification or a prison. The entrance is usually protected in some way, such as with a fixed wall blocking the door which must be circumvented before entering, but which prevents direct enemy fire from a distance. It may include the use of two doors such as with an airlock
An airlock is a device which permits the passage of people and objects between a pressure vessel and its surroundings while minimizing the change of pressure in the vessel and loss of air from it...
Etymology and historical usage
The word port
is ultimately from Latin portus
for door. Often the term postern
A postern is a secondary door or gate, particularly in a fortification such as a city wall or castle curtain wall. Posterns were often located in a concealed location, allowing the occupants to come and go inconspicuously. In the event of a siege, a postern could act as a sally port, allowing...
is used synonym
Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...
ously. It can also mean an underground tunnel, or passage (i.e. a secret exit for those besieged).
ultimately derived from Latin salīre
(to jump), or sortie
Sortie is a term for deployment or dispatch of one military unit, be it an aircraft, ship, or troops from a strongpoint. The sortie, whether by one or more aircraft or vessels, usually has a specific mission....
, is a military maneuver
Military tactics, the science and art of organizing an army or an air force, are the techniques for using weapons or military units in combination for engaging and defeating an enemy in battle. Changes in philosophy and technology over time have been reflected in changes to military tactics. In...
, typically during a siege
A siege is a military blockade of a city or fortress with the intent of conquering by attrition or assault. The term derives from sedere, Latin for "to sit". Generally speaking, siege warfare is a form of constant, low intensity conflict characterized by one party holding a strong, static...
, made by a defending force to harass isolated or vulnerable attackers before retreating back behind their defenses. Sallies are a common way for besieged forces to reduce the strength and preparedness of a besieging army; a sally port is therefore essentially a door in a castle
A castle is a type of fortified structure built in Europe and the Middle East during the Middle Ages by European nobility. Scholars debate the scope of the word castle, but usually consider it to be the private fortified residence of a lord or noble...
or city wall that allows troops to make sallies without compromising the defensive strength of the fortification
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...
Targets for these raids included tools which could be captured and used by the defenders, labor-intensive works such as trenches and mines, and siege engines and siege towers. Sometimes enemy laborers were also targeted. Often, the besiegers' beer and food supplies would be stolen or, if they were too bulky to transport, urinated in.
Modern personnel sally ports are used to control entry into highly protected and restricted military areas, e.g. nuclear weapons storage areas, highly sensitive (and large) conventional weapons storage areas, e.g. small arms, munitions, etc. Sally ports are also used to control entry to highly valuable civilian facilities such as currency or credit card manufacturing sites.
A guard in a protected location (today usually physically remote from the actual sally port) will have control over the middle space between the two doors; the operation of the doors of the sally port; and the movement of all persons, materials and/or vehicles through the sally port. This sally port guard will have the means to check the personnel escorts and/or the credentials of all those persons, materials and vehicles to be passed into the protected space through the first opened door, prior to its opening. He will then monitor the sally transit to ensure that:
- no more than the maximum allowed number of verified individuals/materials or vehicles are permitted and actually do transit into the middle space at any one time;
- all persons vehicles and/or materials are cleared by the controller of the interior protected space (a second, separate individual from the controller of the sally port) to enter that secured space prior to the un-locking and/or opening of the second door;
- the first opened door to the sally port is closed locked and secured prior to unlocking and/or opening the second door; and
- the guard will ensure after the completion of a transit movement of persons, materials and/or vehicles through the sally port, that the middle space of the sally port is clear (empty) of all persons, materials, or vehicles prior to his securing (closing/locking) of the second door, to await the next movement through the sally port.
Sally ports must be used with caution, and transit through them must be carefully monitored during any emergency or non-routine movements. The greatest safety hazard in use of these passageways is the danger of overcrowding the middle space between the doors. Since either door can only be opened while the other is closed and locked, overcrowding may occur in the middle space when too many persons, vehicles or materials attempt to enter it at once.
Once the middle space is overcrowded, it may be impossible to properly close and lock the first door, thereby also making it impossible to open the second door, which of course is the only way by which people, vehicles or materials can successfully exit the controlled area. Even when the sally port has over-rides installed within the door controls and locking apparatus, the size of the middle space and the physical dimensions and layout of the door openings will act to hamper quick egress of a controlled space through a sally port type opening.
Because of this danger, controlled spaces protected by sally ports usually have multiple sally port openings, safety zones within the controlled space (for internal evacuation w/o leaving the controlled area), and formally written and routinely practiced procedures for the evacuation of persons, vehicles or materials. There is also continuous supervision and monitoring of the total number of persons, vehicles or materials within the controlled space to ensure that the designed evacuation maximum (by whatever evacuation procedure) is never exceeded.
Sally ports are also used to restrict the flow of people to one at a time so that intruders cannot pass into the classified or secure area on a cleared person's coattails.
Military vehicular sally ports are similar to the personnel sally ports but have, of physical necessity, a large middle space to control the incoming/outgoing vehicle and personnel mounted in the vehicle. Mounted personnel are made to stand down, and the vehicles are inspected by guards.
If the person or vehicle in the middle space is found to be unauthorized, the guard can "lock down" both gates, trapping the individual in question until a guard or police response force can neutralize and remove the person and/or vehicle.
A sally port appears on the Coat of Arms of the Republic of Malta
In the modern court building, a sally port secures the prisoners in a holding area or brings them directly from the jail area separating them from the court, with entry through the sally port controlled by the bailiff
A bailiff is a governor or custodian ; a legal officer to whom some degree of authority, care or jurisdiction is committed...
Supermax is the name used to describe "control-unit" prisons, or units within prisons, which represent the most secure levels of custody in the prison systems of certain countries...
" correctional facilities, groups of inmate cells may be connected to central corridors via sally ports. An officer behind protective glass opens the port doors individually after verifying that the person is allowed to pass.