Sunday, September 30, 2012

Coronel aftermath -- a solitaire session

The victorious German East Asia Squadron in Chile after the battle of Coronel

As the Battle of Coronel was being fought in the early evening of Nov. 1, the old battleship HMS Canopus was struggling against heavy seas and a balky engineering plant to catch up to Cradock's out-gunned squadron.  Cradock had left the Canopus behind, believing it to be too slow to be useful. Churchill had expected the Canopus to be  a"citadel" that would protect Cradock's weaker armored cruisers should they run into Spee's entire fleet. Spee, for his part, indicated after the battle that he thought he might have lost had the battleship been present.

In the actual event, the British light cruiser Glasgow escaped the massacre and warned the Canopus of the disaster. The battleship promptly turned around and fled -- slowly -- back to the Falkland Islands, eventually being joined by the Glasgow on the way. 

There were innumerable ways that the Glasgow could have failed to get word to the Canopus about the battle's outcome, however, so it's not too much of  stretch to wonder what might have happened if the Canopus had continued north and run into Spee's squadron before he turned around to go to Valparaiso to recoal and reorganize. 

So it's dawn on Nov. 2, and lookouts on the HMS Canopus see smoke on the horizon to the north which soon reveals itself to be coming from the two German armored cruisers Scharnhorst and Gneisenau and the light cruiser Nurnberg. (The Dresden and Liepzig had been detached to scout for the British survivors of the night battle.)

The tactical problem facing the captain of the Canopus is simple. He can't run away, the Germans ships are almost twice as fast. While his 12-inch guns slightly outrange the German 8-inch guns, his slow speed means he can't control the range as well. 

Spee's decision is much more complex. While he won the battle against the British cruisers at a trifling cost in damage and casualties, the battle did expend about half his ammunition. This alone was a very strong argument for avoiding combat worth any new force encountered. He probably only had enough ammunition for one more fight. Prudence would have dictated that Spee use his superior speed to steam away from the Canopus, possibly detaching the light cruiser to keep an eye on the battleship until the British decided whether to press on or withdraw. This is the most likely outcome. 

On the other hand, Spee was a very aggressive commander and it would have been tempting to run up the score, so long as he avoided taking serious damage or using too many of his remaining shells. 

So let's examine how it might have played out. This makes a good solitaire scenario. The Canopus has few decisions to make. It can't run, so it will turn broadside to the approaching Germans and fire as long as it is able.  I'm using the 1970 Victory at Sea rules for this fight. 

Spee, on the other hand, needs to execute his approach with care. The safest thing to do would be to stay at long range, allowing him to safely break off the battle at any point. But long-range gunnery uses up a lot of ammunition for relatively fewer hits. Closing the range will allow the Germans ships to bury the battleship in a deluge of damaging fire -- but risks disaster if a German ship gets badly hit. 

We will assume Spee decides to boldly close the range on the theory that he night as well decline to fight at all if he was to engage in an inconclusive long-range gunnery duel. 

The range is 15,000 yards as the two forces sight each other. The German column is comprised of the Scharnhorst, the Gneisenau and the Nurnburg in that order.

The action commences with HMS Canopus hauling hard to port to bring her broadside to bear, while the German squadron pours on the goal to close the range at 20 knots, angling to port so as to unmask batteries and heading in the opposite direction of the British ship in case it makes sense to disengage later. . The light cruiser turns so as to remain on the unengaged side of the battle line.

At 14,500 yards it's a tough shot for each side. The base "to-hit" chance at that range is "16 out of 36" which is halved to "8 out of 36" for World War I fire control. This translates to a 22.2% chance to hit, or a 3 or a 7 on two dice. All secondary guns are out of range. 

The Canopus rolls a 3 and a 6 for a hit! The 12-inch shell lands on the deck of the Scharnhorst, doing 900 points of damage. The shell does not do critical damage, but it definitely gives Spee pause. 

The return fire from the Scharnhorst is also effective, with one of the twin turrets landing a hit on the deck of the Canopus, doing 1,225 points of damage on the old battleship. While styled a "battleship," the Canopus belt and deck armor is no thicker than the armor on the armored cruisers. The Gneisenau is yet out of range.
At 12,500 yards the broadsides continue at "9 per 36" or a 4 or 7 to hit.  The Canopus lands again on Scharnhorst, this time hitting and penetrating the belt armor for 1,020 more points of damage for a total of  1,920.  More critically, this hit slows the Scharnhorst's speed by 10 knots.  This is the last straw for Spee and he decides it's time to call it a day, especially because none of his return shots from either armored cruiser scores that turn. 

The German armored cruisers start to turn away while the Nurnburg starts to lay down a smoke screen to cover the withdrawal.  A parting shot from the Canopus hits the Scharnhorst again for another 900 points of damage, total 2,820.  The draw for a critical hit, however, provides  a very dramatic end as the Scharnhorst's magazine explodes! 

The Scharnhorst finds the range on the Canopus in return, but the 8.2-inch shell bounces off the belt armor.

The surviving Germans ships withdraw out of range under cover of smoke  and the Canopus is far to slow to chase them.

Well, that little play-through suggests that there was little to be gained by messing with a battleship -- even an indifferent one such as the Canopus! Maybe Churchill was right after all ... 

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