Coehorn mortar?

[bamaman]

Does anyone know what à Coehorn mortar is?

 

[Biscoitos]

Japanese "knee mortars" in WW2 Pacific.
Speaking of smallish very portable mortars, these should be considered.
The name is misleading.

 

[redbob]

Japanese "knee mortars" in WW2 Pacific.
Speaking of smallish very portable mortars, these should be considered.
The name is misleading.

As unfortunately many American military personnel found out when they placed them on their knees when they fired them.

 

[52ndFandS]

Japanese "knee mortars" in WW2 Pacific.
Speaking of smallish very portable mortars, these should be considered.
The name is misleading.

I'd have hate to have been the guy who found out just how misleading the name was.

 

[ErnieMac]

The Coehorn mortar was invented by Menno, Baron van Coehoorn, during the War of Spanish Succession in the 1701 - 1702 time period. One of its early appearances in American history occurred during the Siege of Fort Niagara in September 1759. The commander of the British forces, BG John Prideaux was standing near the British artillery line when one of the mortar rounds exploded prematurely. A fragment of the round struck Prideaux in the head and killed him instantly. Sir William Johnson took command of the British army and successfully concluded the siege.

 

[7thWisconsin]

The Coehorn mortar was invented by Menno, Baron van Coehoorn, during the War of Spanish Succession in the 1701 - 1702 time period. One of its early appearances in American history occurred during the Siege of Fort Niagara in September 1759. The commander of the British forces, BG John Prideaux was standing near the British artillery line when one of the mortar rounds exploded prematurely. A fragment of the round struck Prideaux in the head and killed him instantly. Sir William Johnson took command of the British army and successfully concluded the siege.

Absolutely! Johnson had no authority to command royal troops with his colonial commission, but it was probablly all for the best as far as the British were concerned that he took command. One of the most capable American leaders of the 18th century.

 

[major bill]

The Summer 2026 "The Civil War Monitor" "Salvo Department" covered the Coehorn Mortar. To quote the article "Both sides relied more heavily on Coehorns as the opposing armies increasing dug in over the war's final year."


It says that from February 1862 and January 1865 the Federal government ordered 248 Coehorn Mortars. When the armies dug in was the Coehorn Mortars a game changer?

 

[gary]

The mortar's high trajectory enabled one side to fire from an unseen position and a drop a shell atop an equally unseen opponent. They were very useful in siege warfare. Sometimes they were used in cooperation with waiting marksmen who shot at the enemy when he flushed.

There were mortar batteries back in the Civil War but imperfect spotting and communication for adjustment hampered their effectiveness. Also there was no ToT (time on target) like the British developed later (WW I).

 

[7thWisconsin]

The Summer 2026 "The Civil War Monitor" "Salvo Department" covered the Coehorn Mortar. To quote the article "Both sides relied more heavily on Coehorns as the opposing armies increasing dug in over the war's final year."


It says that from February 1862 and January 1865 the Federal government ordered 248 Coehorn Mortars. When the armies dug in was the Coehorn Mortars a game changer?

Oh yeah absolutely. The Army of the Potomac increased the number of mortars on the line by hundreds of percents in the last year of the war. I think it had 15 in May of 64. The coehorn mortar is ideal for antipersonnel fire in fortifications. High angle fire delivered over a fairly short range while being able to remain largely concealed is a great advantage. And it's man-packable. 4 guys can pick it up and move it, which means that it's less prone to counterbattery fire than a larger gun, or a wheeled field piece. The coehorn is very good for delivering a harassing fire. The target is a fortification, It's not going anywhere, and anywhere you drop a round is likely to do some damage and mortally disturb somebody.

 

[major bill]

At a show. What have we here?

 

[gary]

I should add that they were tactical weapons and not figured in as break-through (concentration at one point to enable a successful infantry assault).

During the F&I War Siege of Fort William Henry, the artillery concentrated at one point and once that bastion was reduced and the fort could be stormed, terms were offered and accepted. The same was being tried against the twin ravelins that constituted the Priest Cap at Port Hudson; but the Confederates surrendered after: (1) food was near exhaustion; (2) supply of percussion caps were low, and; (3) knowledge that Vicksburg capitulated and (4) Nextflix and social media was cut off from the garrsion.

 

[Rhea Cole]

At a show. What have we here?View attachment 583097

Is the cylindrical cast iron version from a Southern foundry? The 12 pound gun-howitzer Napoleons really do look like a length of cast iron pipe.

Admittedly, I am most fond of the Vicksburg tree trunk versions.

 

[7thWisconsin]

Are those tubes original or reproductions? Coehorn mortar reproductions used to be very inexpensive. Partly because of their affordability, they ended up in the hands of people with a sense of safety which was, shall we say, "flexible." That got them banned from many reenacting events outright, or event organizers adding some justification like "this is an early war event, so no coehorn mortars are allowed on the field."

 

[major bill]

Are those tubes original or reproductions? Coehorn mortar reproductions used to be very inexpensive. Partly because of their affordability, they ended up in the hands of people with a sense of safety which was, shall we say, "flexible." That got them banned from many reenacting events outright, or event organizers adding some justification like "this is an early war event, so no coehorn mortars are allowed on the field."

The two in the photo were at the Civil War and artillery show in Ohio. They were on display in the artillery building and not with the reenactors. I did not talk to their owner.

 

[7thWisconsin]

They are lovely pieces. Ft Ligonier in Pennsylvania has a wonderful collection of 18th century artillery including a bunch of Coehorn mortars. Every time I see them it awakens mortar envy in my heart.

 

[13 IL Cav & 64 GA Inf]

At a show. What have we here?View attachment 583097

Great post.

 

[gary]

"The coehorn mortar is a most valuable weapon in siege operations. From its lightness and portability, it is peculiarly well adapted to the attack, and should follow close on the heels of the sappers." - Quincy Gillmore.