Sorry if this is a dumb question, but why would it not be possible just go round a shield wall and attack the flank? Take the Battle of Hastings. William I first had cavalry so he surely could have outmanoeuvred Harold Godwinson's shield wall, but he famously was unable to break through and would have likely lost if his opponents hadn't messed up and broken ranks. The only thing I can think of is if the shield wall completely surrounds the unit, but then that's leaving you open to being surrounded which doesn't seem like it would be a good strategy. Am I completely missing something here?
Hello.
A preliminary note: Harold was stationed on top of a hill and the Norman cavalry basically had no manoeuvering ground. Also,unlike video games, if cavalry charges are unsupported by infantry they are weak. Keep in mind unlike the Hunnic cavalry, or Polish Winged hussars or something, the Norman cavalry were not specialists to do standalone actions. The Saxons were in solid formation, you cannot expect victory with a cavalry charge when formations are solid and consisting of heavy infantry.
Now let us take a look at why you cannot go around a shield wall. Let us imagine a 100vs100 battle, one side having a shield wall. In order to get around this shield wall you would basically have to encircle it right? That is when your formation gets thinner and thinner and you lose all your advantage of having a formation at all: discipline and fighting together. At that moment the shield wall can just break and now the shieldies are still fighting together but the other side is, although encircling the shieldies, is all over the place and dispersed. They are now in 10-20 men groups around a group of 100 people. These people can now be easily even more isolated and cut down.
Now imagine this in a large battle. Almost no communication, very wide formations, etc. The same question can be asked why Persians simply didnt outflank the Macedonian and their phalanx in Gaugamela, since they had 3 times more men. But poor communication and poor average morale leads to routs if you decide to bend your formation just a tiny bit.
Note: there is a scene in the Vikings tv series in which a 10 men Viking shield wall is able to hold the regular Saxons. To be honest I wouldnt know how the Saxons did not flank the wall as the numbers are miniscule, it is probably just for the show. But remember,real battles: Formation,morale, discipline, terrain, communication, concentration etc.... All these factors must be considered when you decide to break formation and encircle the enemy.
The best example of this is the battle of Cannae but that battle is actually 5 times more complex than it looks and is the perfect execution of encirclement. By studying how perfectly the plan was executed can you understand how hard it is to encircle enemies