US Ironclads in Service and the Passaic class.Monitor

In a recent "discussion" on an internet forum I was "informed" that the USN had dozens of Monitors and they'd sweep the seas of the British. My response was to post figures showing that at no point did the USN actually have more armoured ships available for service than the RN. One of the offshoots was I made a chart showing US ironclad strength (excluding the Mississippi flotilla, which were not really ironclads, although the fact this chart excludes the Milhawkee class of river monitors is debatable).



What is apparent is that the Passaic class Monitor are the absolute backbone of any defence of the US during the period when the RN might intervene (i.e. upto July 1863). Starting the early 1864 the USN ironclad force becomes much more powerful as the Canonicus and other 15" armed Monitors start to come into service, although about this time the RN starts putting ordnance into service capable of piercing Monitor turrets at extreme ranges.

The Passaic was an improved Monitor, although the design work was done before the US had actually fought the Monitor. 10 units were ordered at a contract price of ca. $400,000 each, now of which was reached. The cost per unit was more than double that of Britain 1854/5 ironclads (at a fixed £1 = $3 exchange, which in reality flutuated immensely) and the cost of 2 Passiacs would purchase a Defence or Hector class for the RN, and 3 Passiacs would purchase a Warrior or similar. A Passiac cost about the same as a two deck steam ship-of-the-line. They were not cheap vessels by any stretch of the imagination.

They were fairly large, 200 feet long, 46 feet in beam and had a draught of 11 ft 6. Builders measurement was 844 tons, placing them in the same size class as a sloop of war. This makes them far too large for much riverine work (they could not transit the St. Lawrence for example). The engines were the same Ericsson vibrating lever type used in Monitor, but pushing a larger vessel. At 320hp the Passiacs could approach 7 knots with clean bottoms, however after any period at sea due to their lack of coppering barnacles rapidly reduced their speed below 4 knots. Her turning circle is, at 350 yards, high for a monitor (Onondaga had a turning circle of 260 yards, and Dictator 230 yards, even the Russian copies had much tighter turning circles), and about the same as an RN ship of the line or 2nd class armoured frigate (the much finer 1st class armoured frigates often had much larger turning circles, Warrior's being measured at 760 yards at 12 kts, although a "mere" 608 yards at 5 knots).

Armament was designed to be 2x 15" Dahlgren guns. However, the lack of such ordnance meant only one per ship could be supplied, and they were armed with a 15" and a 11" for the most part. The guns could be reloaded in 7 minutes. Against armoured vessels only the 15" really matters, but against wood the 11" would have been effective. The real problem was that the 15" gun completely blocked the port, the gunners could not aim the piece, hence the entire turret was aimed using the 11" gun, and the 15" gunners simply fired when the 11" gunners fired. Since the guns have differing angles, this meanbt that shooting the 15" above 300 yards (point blank range) was an exercise in futility. I can only speculate how the gunners of Cammache (which had 2x 15") and those of the post-ACW Passaic (also with 2x 15") actually aimed their guns.

Armour was originally as Monitor (which had been uparmoured after Hampton Roads), 11 x 1" plates on the turret, 3-5 x 1" plates on the hull and a single 1" plate on the deck. This proved inadequate at Charleston in 1863, and all were uparmoured in places, notable armoured rings were placed around the turret bases as even the most minor damage in that area would jam the turret. The turret is unlikely to be pierced by any weapon at sea in 1863, although the Battle of Charleston showed that the guns could be knocked out by concussion very easily. The hull is much more vulnerable, especially against a vessel whose guns have reasonable height, since the deck would start to take strikes.

Whilst a useful ship, the Passaic is not a competitor for most European ironclads. The best matchup would be against an old Crimean War ironclad, which has similar speed and handling characteristics, although is heavier armed. I retain my doubts that the Passaic would be 50/50 against a wooden frigate.

Confederate Meaning of "Effective"

It seems to be generally taken that when the Confederates say "effective" they are only including enlisted combatants, a position I have previously subscribed too. To wit, US Grant wrote in Century Magazine:

"The effective strength of the Union force on the morning of the 6th was 33,000 at Shiloh. Lew Wallace brought 5000 more after nightfall. Beauregard reported the enemy's strength at 40,955. According to the custom of enumeration in the South, this number probably excluded every man enlisted as musician, or detailed as guard or nurse, and all commissioned officers -- everybody who did not carry a musket or serve a cannon. With us everybody in the field receiving pay from the Government is counted. Excluding the troops who fled, panic-stricken, before they had fired a shot, there was not a time during the 6th when we had more than 25,000 men in line. On the 7th Buell brought 20,000 more: Of his remaining two divisions, Thomas's did not reach the field during the engagement; Wood's arrived before firing had ceased, but not in time to be of much service. Our loss in the two-days' fight was 1754 killed, 8408 wounded, and 2885 missing. Of these, 2103 were in the Army of the Ohio. Beauregard reported a total loss of 10,699, of whom 1728 were killed, 8012 wounded and 957 missing: This estimate must, be incorrect. We buried, by actual count; more of the enemy's dead in front of the divisions of McClernand and Sherman alone than here reported, and 4060 was the estimate of the burial parties for the whole field. Beauregard reports the Confederate force on the 6th at over 40,000, and their total loss during the two days at 10,699; and at the same time declares that he could put only 20,000 men in battle on the morning of the 7th."

In fact, whilst reading the OR's it has become clear to me that their meaning of "effective" is simply the number of not-sick enlisted men, see Rodes' state going into Gettysburg for an example(ref).

By the statements of the two armies commanders Shiloh was 20,000 Confederate combatants wrestling with 25,000 Federals. It's food for thought.

Lee Letters

An interesting find on archive.org, Lee's Despatches not included in the OR: http://www.archive.org/details/cu31924030913978

The 1862 Defence Plan for Canada

Over a year ago I visited the PRO at Kew and read the defence plan for Canada published in mid-1862. To the best of my memory (having lost a sheet from my pad) it was published in WO33/11.

The defences and dispositions were:

Military District 1 (London)

Permanant Works
Fort Edward at Sarnia: 500 men and 20 guns
Fort Malvern and a Fort on Bois Blanc Island at Amherstburgh, both 500 men and 20 guns
A fortified place of arms at Sarnia with 1,000 men and 50 guns

Temporary Works
North and south side of Goderich Harbor, east and west side of Port Stanley, and the mouths of the Thames River and Sydenham, each with 150 men and 10 guns

Entrenched positions at London, Paris and Chatham with ca 11,600 men

Military District 2 (Toronto)

Permanant Works

On the Niagara frontier and Welland Canal:
Fort Erie with 500 men and 20 guns
Fort Mississagua with 500 men and 20 guns
Port Dalhousie with 300 men and 15 guns
Port Colborne with 200 men and 10 guns
A fortified place of arms with 1,000 men and 50 guns

At Burlington Bay (Hamilton) a battery with 100 men and 6 guns
At Toronto New Barracks 500 men and 25 guns
New naval dockyards to be constructed at Dunnville and Port Maitland

Temporary Works
Opposite Black Rock on the Niagara River; a battery with 150 men and 5 guns
At the entrances to Collingham and Sydenham Harbours; 150 men with 10 guns each
At Port Hope several batteries totalling 400 men and 20 guns

Entrenchments on the Queenstown Heights (a Corps of Observation of 10,000), in front of Hamilton and at Toronto near the Holland River (2,200 between the two)

Military District 3 (Kingston)

Permanant Works
At Kingston; Murney Tower, Shoal Tower, Market Battery, Cedar Tower, Fort Henry and Fort Patrick totalling 94 guns (no manning figure, but by inspection 3,300 men in the district are remaining after other positions filled)

Prescott: a fort with 500 men and 20 guns
Bay of Quinte: a new naval dockyard

Temporary Works

Port Cobourg: a battery with 100 men and 5 guns
Kingston Mills: a fort at the mouth of the canal with 500 men and 12 guns
Brockville: a battery on a St Lawrence river island with 100 men and 10 guns
An entrenched camp at Prescott with 500 men

A field division of 5,000 men to be based at Prescott

Military District 4 (Montreal)

Permanant Works
Montreal: Citadel with 2,000 men and 50 guns, St. Helen's Island with 500 men and 15 guns, St. Lambert's Island and Tete de Pont with a total of 400 men and 40 guns

St Johns: the fort was to be rearmed with 20 modern guns
Isle aux Noir: this fort was also to be rearmed with 20 modern guns

Temporary Works
Cornwall canal: 200 men and 10 guns to protect of locks
Coteau du Lac: on the site of the old fort a battery of 100 men and 4 guns


At Montreal:
Vandreuil: 200 men and 10 guns
Isle Perrot: 300 men and 20 guns
Nun's Island: 300 men and 20 guns
St. Lambert: 600 men and 40 guns
St. Helen's Island: 30 guns to reequip the existing garrison
Bout de l'isle: 150 men and 10 guns
Lachine: 150 men and 10 guns

St John's, at Tete du Pont 200 men and 15 guns
Chambley, at Tete de Pont 150 men and 10 guns
Richmond, redoubts with 400 men and 25 guns

Entrenchments west of Montreal Mountain, at Sherbrooke and at St. John's with 10,650 men (including some manning works above, probably 10,000 troops in the field force)

Military District 5 (Quebec)

Permanant Works
Repair of Quebec Citadel, the addition of a battery of 10x 110 pounder rifles and a new work replacing the old French works with 200 men and 15 guns (number garrisoning the Citadel unknown, but probably 2-3,000)

Point Levi: enclosed work with 500 men and 30 guns

Temporary Works
On the left bank of the St. Charles a battery of 200 men and 12 guns, and an entrenched position on the Plains of Abraham
At Riviere du Loup, 200 men with field artillery to protect the railway, at Fort Ingall and Black Rover another 100 men each with field artillery also protecting the railway

Naval force:

A force of 550 guns manned by 9,350 men, including 9 small ironclads to be placed on the Lakes

Manpower:

The planning figure for Canada is 50,000 regulars and 100,000 militia. Around 20,000 militia are in the garrisons above, leaving 130,000 for the field army. Around half this field force is spread out in 5 Corps de Observation of 10,000 men at 1 per military district. The remaining 60-70,000, including the bulk of the regulars, were to form a field army to counterattack any US invasion force.

This of course excludes the Maritimes, which expected to receive 25,000 regulars, 25,000 militia and a force of 10,000 British militia to guard Halifax.

Slightly OT: Hits per round at Vittoria (1813)

This is slightly OT, but as it's a commonly used comparitor (not least in Nosworthy's The Bloody Crucible of Courage) I thought it was appropriate to put here. Sorry for the digression into the Napoleonic War.

A commonly quoted figure of musket rounds fired per hit achieved is 1 in 459. The source of this figure is Henesay (original source). However his figures do not add up. For a start, only 3 British Divisions were heavily engaged at Vittoria (2nd, 3rd and 5th); only 10 British and 3 Portuguese regiments, and the Royal French Chasseurs Brittanique suffered more than 100 casualties. The 3 heavily engaged divisions had marching states of ca. 25,000 Officers and Present Under Arms on their state of 25th May, and had been marching and skirmishing for nearly a month before the main event. Henesay's count of 50,000 engaged infantry is highly unlikely. Also, the nature of the fighting at Vittoria precluded many standup musketry duels. While some may have occurred at river crossings, most of the real fighting was close quarter bayonet work, especially for the 3rd Division.

So, if Hennesay's estimate of over 3.6 million rounds fired is inaccurate, do we know how many rounds were fired? Yes, Henesay himself gives that information.

The way ammunition resupply worked on the Peninsula was that boxes of ball-cartridge were dropped by the Commissary behind companies, who would then send small details back to open them and distribute the rounds, the soldiers cartridge boxes were kept constantly full. Henesay's figures indicate that 1.35 million rounds were thus distributed. However Henesay notes only roughly half of these were fired. Thus we arrive at the approximate number of rounds the British actually fired, about 675,000, which is well within the norms for European combat (which reckoned on 20 rounds per infantryman being used in a battle).

Henesay's estimate of casualties is too high. The French Armies suffered 5,210 killed and wounded, exclusive of much of their artillery (no returns except for the Army of the Centre, whose artillery was overrun at bayonet-point) or the attached Spanish Royal Guards or elements of the Army of the North. Oman estimates (from pro-rating officer casualties, which were recorded) hundreds of extra casualties, probably, in my opinion between 5,700 and 5,900.

The proportion of these hit by artillery will never be known, but the artillery played little role in the British attacks, since the infantry kept outrunning their artllery support. If we make the assumption that no-one was hit by artillery then the proportions of musket rounds expended per hit is about 1 per 116. This is a high estimate, and in all probability the real ratio is in the 1 in 150 to 1 in 200 range common in American Civil War firefights.

Confederate Straggling in Maryland and Lee's strength at Antietam

I'm interested in just how badly the Confederate Army straggled in Maryland. Using the 22nd September field returns (ref), the casualties in the campaign (from Harsh's Sounding the Shallows, supplemented by the OR's to add in South Mountain casualties) and the estimated strength 2nd September as reported in Harsh.

Longstreet's Command

• DR Jones straggles heavily. Of his 8,615 man division only 4,403 are with him on 22nd September and 1,435 are casualties, leaving 2,777 stragglers (32%).

• Hood's and Evan's "divisions" have 4,834 on 2nd September, but only 3,403 on the 22nd, with 1,109 casualties. Therefore they do not straggle badly and have only lost 322 (7%),

Jackson's Command

• Jackson's own division enters the campaign with 5,650 and has 3,494 on the 22nd, after losing 648. Thus they straggle heavily with 1,508 (27%) disappearing. In his report Jackson seems to try and cover up the straggling by moving these into the killed and wounded, exaggerating how hard his division fought (sustaining more casualties than Jackson reported with the colors on the 17th).

• Ewell's division (under Lawton then Early) entered the campaign with 6,383, lost 1,338 and had 4,066 left on the 22nd, implying 979 stragglers (15%)

• The Light Division enter the campaign with 8,570, lost 417 but only have 5,468 on the 22nd, losing 2,685 stragglers (31%)
  

The other divisions

• DH Hill did not suffer badly from straggling, of his 9,764 on 2nd September, 5,821 are with him and 3,241 as casualties for a balance of 732 (7%) straggling.

• Walker did not suffer badly either. Of his 5,159 he still had 3,871, despite losing 1,120 at Antietam for a difference of 168 (3%).

• McLaws suffers terribly. Of 7,652, he only has 4,018 remaining, after 1,119 casualties. 2,515 men (33%) have straggled out of the ranks

• Anderson's huge division of 11,294 straggles badly. He has only 6,298 remaining on the 22nd after 1,278 casualties. 3,718 men (33%) have taken leave from him.

There is a general pattern. The formations which executed the more arduous marches had the stragglers. The general implication is that ca. 15,404 men were lost to Lee for the battle of Antietam.

If we take the 22nd September morning state, add back in the Confederate casualties for Antietam, and remove Thomas's brigade (absent the field) we arrive at a figure of roughly 50,000. Adding in the cavalry and half the artillery reserve we have roughly 55,000. This is probably close to the strength of Lee's army on the field on the 17th.

McClellan, the Signal Corps and his time on USS Galena

The Signals Corps

There are many claims made about the nature of the American Civil War being novel. Many of these are spurious but some are true. One of the most "modern" features of the ACW is the activities of the United States Signal Corps. This small and overlooked body of men ran a tremendously effective communications system. Communiques McClellan sent from a field command post on the outskirts of Richmond would arrive at Washington, DC a mere ten minutes later. Using this system McClellan was able to achieve a level of command and control of his Corps as then unrivaled in the world. Indeed this was the first Signals Corps created in the world ever (in the British Army, for example, Signals would remain a part of the Engineers for decades).

McClellan wasn't working in a void. He'd seen the advances in communications technology made by the armies of Europe, and resolved to implement them fully. The general history of the Signals Corps during the war can be read on wikipedia.

The electric telegraph was short ranged and unreliable. A semaphore based system, the "wig-wag" worked very well within line of sight. It was the wig-wag that McClellan would use to control his army before Richmond. Such "frippery" as signals didn't emerge in the Army of the Tennessee for over a year (although it was very advanced in the Army of the Ohio/ Cumberland), the likes of Grant and Sherman simply had no time for it.

McClellan thus commanded his army from a central command post with signals to the subordinate commands (divisions, even after the establishment of Corps). He could leave his CP and, as long as he had an efficient signals troop with him, he could maintain command of the battle from anywhere.

Glendale and Malvern Hill

This brings me to the accusation that McClellan abandoned his army at either Glendale or Malvern Hill (both are sometimes mentioned), and to the related issue of the fantastic tale of an army commander having lunch on a boat off shore while his army fought.

It is important to note that McClellan established his General Headquarters Command Post at Haxall's Landing on Malvern Hill. From this position he was in communication with all his commanders and with the naval force on the James River (by way of a signals detachment sent on board her).


Figure 1: approximate schematic of McClellan's signals at Glendale (Porter's two divisions preparing positions on Malvern Hill omitted for clarity)

At Glendale, McClellan placed his divisions personally earlier in the day. He had effectively adopted a taskorg of three wings, one at White Oak Swamp with 3 divisions under Franklin, Sumner and Heintzelmann had a line facing west, whilst Keyes and Porter were detached from the main line on other tasks (Keyes would march with the army's trains to Harrison's Landing, whilst Porter was preparing a fallback position and acting as a reserve). He had direct contact with the four divisions to the west and contact with a relay station on the northern flank that connected the other 3 divisions in the line. He also had communications with Porter (whose signals were higher up on Malvern Hill and relayed a lot of intelligence). Keyes was marching, but may well have kept in contact with Porter after he broke contact with McClellan.

According to the report of McClellan's signals detachment show after fighting started McClellan went to the front to check, returned to his CP, then went to the fleet. Whilst with the fleet he maintained contact with all his commanders via his signals and received their reports. He directed the naval gunfire that decisively defeated Holmes's movement (and Lee's battleplan) personally. He then returned to shore and his CP.

The next day, after the withdrawal to the prepared killing area of Malvern Hill. He didn't sleep that night, inspecting positions and positioning divisions, and around 9am boarded the Galena for a personal recce of Harrison's Landing and to consult with the naval commander. During this period he would still have been in contact with his commanders. He had 3 signals stations that could view the river; one at Haxall's Landing, one on Malvern Hill and one at Harrison's Landing. He left the Galena at 1330hrs (after having given the order to open fire with the artillery on the massing Confederates) and was on the field at 1400, over 90 minutes before the Confederate attack. He was thus present for the battle.

Conclusion

On of the great overlooked achievements of the Union Army during these battles is that the commanding general could be anywhere, even miles down a river on a recce. General McClellan commanded from many different places during the battles, but he was always in command.