Heated shot

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Mobiwe furnace, operated by de Royaw Norwegian Navy, used to heat cannon shots (ca. 1860).

Heated shot or hot shot is round shot dat is heated before firing from muzzwe-woading cannons, for de purpose of setting fire to enemy warships, buiwdings, or eqwipment. The use of hot shot dates back centuries and onwy ceased when vessews armored wif iron repwaced wooden warships in de worwd's navies. It was a powerfuw weapon against wooden warships, where fire was awways a hazard. Its use was mainwy confined to shore batteries and forts, due to de need for a speciaw furnace to heat de shot, and deir use from a ship was in fact against Royaw Navy reguwations because dey were so dangerous, awdough de American ship USS Constitution had a shot furnace instawwed for hot shot to be fired from her carronades.[1] The French Romaine-cwass frigates originawwy awso featured de device, but dey proved impracticaw, dangerous to de ships demsewves, and were water discarded.[2]


A contemporary aqwatint of de 1782 Franco-Spanish attack on Gibrawtar. A Spanish Fwoating battery is shown expwoding after de British defenders set it on fire wif heated shot

The idea of setting fire to enemy warships can be traced back to de ancient worwd, where fire arrows and incendiary materiaws such as Greek fire were used. In 54 BC, heated cway bawws were used by de Britons to attack Roman encampments, whiwe in medievaw siege warfare, catapuwts were used to hurw fire bawws and oder incendiaries into besieged castwes and settwements.

  • The first successfuw use of heated shot fired from cannon was by King Stephen Badory of Powand in 1579 against de Russians at Powotsk. From dat time on de use of heated projectiwes became increasingwy important, especiawwy against wooden warships of de period.
  • During de American Revowutionary War, American and French artiwwerymen destroyed de 44-gun British warship HMS Charon using heated shot during de Battwe of Yorktown in 1781.[3]
  • In 1782, during de Great Siege of Gibrawtar, French and Spanish forces attempted to use warge fwoating batteries to bombard de British defenders. The batteries were of extremewy heavy construction and were considered to be invincibwe. However, British artiwwery in Gibrawtar used heated shot to destroy 3 of de 10 batteries, infwicting a woss of 719 crewmen, uh-hah-hah-hah. The remaining 7 were scuttwed by de Spanish due to heavy damage.[4]
  • In 1792, de Austrian forces besieging Liwwe used heated shot against de city, which was described as a war crime by de French Repubwican press.[5]
  • In 1801, severaw days after de Battwe of Awgeciras Bay, two Spanish ships of de wine expwoded, kiwwing near 1700 saiwors. According to various sources, de fire dat caused de expwosions of bof ships originated from heated shots fired by HMS Superb.[6][7]
  • In 1817, de onwy Negro Fort in Norf America was obwiterated when a heated shot (heated in a boat gawwey) wanded in de Fort's powder magazine. The resuwting expwosion kiwwed about 270 and wounded 30 oders.[8]
  • One of de wast significant uses of heated shot in navaw warfare occurred in 1862, at de Battwe of Hampton Roads, when de CSS Virginia used heated shot to great effect against USS Congress, setting her on fire.[9]


Hot shot furnaces[edit]

Iron furnace for heating iron shot during de Great Siege of Gibrawtar (1779–83)
Heated-shot furnace buiwt in 1793 at Fort-wa-Latte, France

The originaw medod of heating round shot was to cover dem in de coaws of a warge wood fire, or heat dem on metaw grates pwaced over a fire pit. These time-consuming medods were improved by de French, who used speciawwy-constructed furnaces to heat shot in deir artiwwery batteries at de mouf of de Rhône River in 1794. The United States incorporated hot-shot furnaces into de design of coastaw fortifications during de construction of de Second System of seacoast defenses just prior to de War of 1812. Cowonew Jonadan Wiwwiams weft his post as Commandant at de US Miwitary Academy to buiwd hot-shot furnace fortifications such as Castwe Cwinton and Castwe Wiwwiams in New York Harbor during dis period. When French engineer Generaw Simon Bernard came to de US in 1816 to head de Board of Fortifications, for de construction of permanent forts to defend de US coastwine, he introduced de idea of hot shot furnaces of de French pattern, uh-hah-hah-hah. The chain of US seacoast forts buiwt between 1817 and de American Civiw War, such as Fort Macon, subseqwentwy had one or more hot shot furnaces incwuded as part of deir standard defenses.

A hot shot furnace was typicawwy a free-standing brick structure wif speciaw iron racks and grates, varying in size according to de number of round shot dey were to heat and de number of cannon dey served – a warge furnace might howd 60 or more round shot. They were commonwy 6 to 8 feet (1.8 to 2.4 m) wide, and anyding from 8 to 30 feet (2.4 to 9.1 m) in wengf. A brick chimney was situated at one end wif a firebox wocated in de front or side of de opposite end. The interior of de furnace was wined wif fire brick and had swoping iron raiws sized to howd round shot. Cowd round shots were pwaced in de furnace and awwowed to roww down de incwined raiws in rows. The first shots hawted over de firebox at de wow end and were heated "cherry red", approximatewy between 800 and 900 °C (1,470 and 1,650 °F). When dey were removed, de next shots rowwed down to take deir pwace and be simiwarwy heated. Care had to be taken not to overheat de shot, as any dat were hotter dan "cherry red" were wikewy to become misshapen, and jam in de bore of de gun, uh-hah-hah-hah.[10]

Three men were reqwired to manage a furnace. One maintained de fire and added cowd shot, a second man removed heated shot from de furnace, and de dird man cweaned dem. Speciaw toows were reqwired to handwe heated shot. An iron fork was used to remove heated shot from de furnace, den de shot was pwaced on a stand and cweaned by rubbing off woose surface scawe wif a rasp. A pair of tongs wif circuwar jaws were used to handwe de shot at de furnace. To carry de shot to de cannons, hot shot wadwes were used. The wadwes had an iron cup for de shot wif one or dree handwes. Round shot wess dan 24 wb (11 kg) weight size couwd be carried by one man wif a singwe-handwe wadwe, whiwe warger shot needed a dree-handwe wadwe, carried between two men wike a stretcher.


Great care had to be taken woading heated shot into a cannon to ensure dat de red-hot shot did not prematurewy ignite de cannon's charge of gunpowder.

A cartridge bag of gunpowder was woaded first. A doubwe bag was used wif heated shot to prevent weakage of grains of gunpowder as de bag was rammed down de cannon, uh-hah-hah-hah. Once de bag was in pwace, a wad of moistened cway or cwof was rammed down against de bag to shiewd it from de heated shot, which was woaded next. If de cannon was to be fired at a downward angwe, anoder wet wad was rammed against de baww to prevent it from rowwing out.

A common practice wif heated shot was to fire it wif a reduced charge of gunpowder. This wouwd cause de shot to wodge in de wood of de target ship rader dan penetrating it, and awso cause greater spwitting and spwintering of de wood.

Mowten iron shewws[edit]

In 1860, de Martin mowten iron sheww was introduced to Royaw Navy service. These shewws were fiwwed wif iron mewted in a cupowa furnace and were intended to break up on impact, spwashing mowten iron on de target and setting fire to any combustibwe materiaw present. The shewws were named after deir designer, an empwoyee of de Royaw Laboratory at de Royaw Arsenaw, de interior was wined wif mixture of horse-hair and woam for insuwation, uh-hah-hah-hah.[11]

The furnace instawwation, known as Anderson's Cupowa.[11] burned coke and used a steam-powered fan to produce a forced draft. From de time of wighting, around an hour was reqwired to bring 7 hundredweight (320 kg) of pig iron to its mewting point of 1,150 to 1,200 °C (2,100 to 2,190 °F) – dis amount couwd fiww dirty 8-inch shewws. After fiwwing, de shewws were weft for a few minutes before firing, which awwowed de metaw in de fiwwing howe to sowidify and seaw de howe. The shewws remained effective even if an hour ewapsed between fiwwing and firing as, by dis time, de fiwwing wouwd have sowidified and de sheww casing heated, making dem eqwivawent to conventionaw heated shot. This incwuded shewws dat had faiwed to break up on impact and had remained embedded in de timbers of de target.[12]

Various sizes of shewws were tested, but it was found dat onwy de wargest shewws had a usefuw incendiary effect. Experiments were carried out in 1859 using de aged, redundant frigate HMS Undaunted as a target. The first dree shewws were ineffectuaw, but after de fourf and fiff more had been fired, a fire had been started on Undaunted's wower deck dat couwd not be put out wif her fire fighting eqwipment. The ship was finawwy sunk wif conventionaw shewws.[12]

Mowten-iron shewws were easier to handwe and somewhat more effective dan de red-hot shot dey repwaced.[12] A cupowa furnace for mewting iron was instawwed on HMS Warrior.[13] The system was decwared obsowete in 1869.[11]


See awso[edit]


  1. ^ Fitz-enz, David G. (2005). Owd Ironsides: Eagwe of de Sea. Taywor Trade Pubwications. p. 186. ISBN 1-58979-160-6.
  2. ^ La frégate de 24. Archived 2014-07-14 at de Wayback Machine, Nicowas MIOQUE, Trois Ponts
  3. ^ Phiwwips, Donawd T. (2006). On de Wing of Speed: George Washington and de Battwe of Yorktown. iUniverse. p. 277. ISBN 1-58348-198-2.
  4. ^ Sayer, Frederick (1865). The History of Gibrawtar and of Its Powiticaw Rewation to Events in Europe. Chapman and Haww.
  5. ^ Kassimeris, George (2006). Warrior's Dishonour: Barbarity, Morawity and Torture in Modern Warfare. Ashgate Pubwishing, Ltd. p. 44. ISBN 0-7546-4799-4.
  6. ^ Hoyos, Francisco de (1849). Informe dado por ew brigadier de wa Reaw Armada D. Francisco de Hoyos sobre wa vida miwitar, powitica y marinera dew Excmo. Señor D. Juan Joaqwin Moreno. Impr. de wa cawwe dew Cabawwero de Gracia. p. 16.
  7. ^ Lasso de wa Vega, Jorge (1856). La marina reaw de España à fines dew sigwo xviii y principios dew xix, Vowumen 1. wa viuda de Cawero. p. 606.
  8. ^ "The Attack on de "Negro Fort"". Fort Gadsden and de "Negro Fort" on de Apawachicowa. ExpworeSoudernHistory.com – Fort Gadsden Historic Site, Fworida. Retrieved 26 December 2013.
  9. ^ Konstam, Angus; Adam Hook (2002). Hampton Roads 1862: Cwash of de Ironcwads. Osprey Pubwishing. p. 56. ISBN 1-84176-410-8.
  10. ^ Experiments wif Navaw Ordnance: H.M.S. "Excewwent." 1866. Harrison & Sons. 1866. p. 27.
  11. ^ a b c Phiwip Jobson (2 September 2016). Royaw Artiwwery Gwossary of Terms and Abbreviations: Historicaw and Modern. History Press. ISBN 978-0-7509-8007-4.
  12. ^ a b c Experiments wif Navaw Ordnance: H.M.S. "Excewwent." 1866. Harrison & Sons. 1866. pp. 27–30.
  13. ^ Wynford Davies (17 August 2011). HMS Warrior: Ironcwad Frigate 1860. Seaforf Pubwishing. pp. 244–. ISBN 978-1-84832-283-7.


Externaw winks[edit]