Is this just Television writers having trouble staging the pushing and grinding forces of shield wall combat, or were there actually shield wall tactics in this period where soldiers knelt to protect the legs of their compatriots, forming an almost literal wall?
according to bayeaux, pretty tight:
The shield wall tactics are not entitled only to roman origins, almost any culture that develops heavy shields will develop a close formation to take advantage of them.
Taking in count the influences of roman military in Brittania, and that during the late empire ( ~400) those tactics were still used and adapted to more "barbaric" combat forms like spear + shield
A shield wall formation could be as tight and as complex as the officers in charge would have been able to imagine and to teach, adapted always to their combat style, ofcourse.
Best explanation of a shield wall I've ever seen can be found on YouTube.
It was rows of men standing...no one in their right mind would try one of those triple-stacked "shield walls" shown on "Vikings" or "Last Kingdom," since you'd be immobilized and blinded. The Roman "testudo" was a formation specifically for siege warfare, and it was mobile because the first row of shields was NOT on the ground.
Remember that neither the Danes, nor the Saxons, nor any Germanic force (aside from the Frankish army) were full-time professional soldiers. Any formations used had to be simple enough not to require constant large-unit training, ans flexible enough to react to attacks from different directions. Armies were small (5,000 was a HUGE force), so one would almost always have open flanks. An immobile, complex, blind formation like these triple-stack shield walls would simply not work.
The typical Viking shield would be an awkward tool to put in a wall. They were light weight and held out straight (like one might mimic with a trash can top) ideal for jabbing an opponent... and defensively could easier deflect the force of a blow... as compared to a heavier hardwood or steal shield, which were held by a handle and forearm strap, which had more limited mobility but could absorb more force without redirecting it. Much better choice for a sturdy formation like a true shield wall. That doesn't mean formations of men might not each purposefully cover the guy on their left, but an actual wall only makes sense in fiction.
I think the answer is overlooked - the different objectives and predominant strategies of assailants.
Viking forces relied on swift attack, mobility. That is; their objective/tactic was to arrive quickly (enabled by having better ships), attack forcefully and achieve an objective and leave BEFORE reinforcements could arrive. Their predominant weapons (spear, shield and axe) were not only cheap but were light and ideal to a highly mobile manoeuvre.
The opposing Saxons' main advantage was that they were on home ground - and if they could stand fast they'd have reinforcements arriving (if Harold, for example had managed to "hold" his troops in line for just a few hours longer, his force would have been greatly multiplied - and perhaps even formed a second front, and William would have had no chance whatsoever - William knew this, which is why he kept the attack up for so long).
It therefore suited the Saxons to stand fast - to form a true wall to simply provide a way to keep the Danes on the field, engaged and effectively trapped.
It suited the Vikings to smash the wall - hence the true effectiveness of the Danish Axe.
The result is determined by achievement of these aims. If the Vikings broke through - they'd get a chance to do damage and then leave. If the Saxon wall held, the Vikings would be routed from all directions.
The circular shields, in my opinion, also were wrong in the depiction of a testudo formation against arrows... which was a Roman formation..
My point is that if you kick into one shield, it won't matter because you kick into 3, since there are nearly 50% of two other shields pressing forward too. That makes the operator of a shield able to work the spear or axe at better and more relaxed conditions.
Since they had axes (as well as spears), the shield wall would benefit them since destroying a shield is best done with an axe.
Their own shields were made of relatively soft wood, light and fairly easily destroyed, but also things get stuck in it and would take energy to both pull out and strike back in. Their axes do huge damage and can also be demoralizing because the pain and energy from each axe blow is felt very well.
I may also add that it's most likely the two shield-men who are behind each side of the front shield that do the attack, as they are only support and can lower their shield to strike hard with their weapon.
I think that the shield-wall can be used in several different ways. I say this more as a historical fan than a fan of The Last Kingdom (because let's be honest, the shield-wall in Vikings was absolute garbage and wouldn't protect them at all). The way the shield-wall in The Last Kingdom worked was that there were three tiers or ranks that they placed. The first rank would kneel and have their shields at the base of the wall, which would allow them to strike the enemy's lower body, like the legs and the knees. The second rank would stack on top of the base. This is the area where the soldiers would be able to attack the chest and neck of the enemy, so they're level with each other. The third rank would allow the men to be protected from above, keeping the enemy from efficiently striking the men in the wall with axes or swords from a downward swing. They generally didn't try and attack due to them having to hold the shield above the head.
A lot of people say, "Oh, well the shield-wall wouldn't work that way because the men needed a lot of training to be able to keep that formation." Well, that's true. However, the whole reason for the shield-wall historically was to keep the enemy in position so there could be a flanking maneuver. The men inside of the shield-wall wouldn't want the wall to break at all, because as soon as it does, it's nearly impossible to reform a line. So, with that, they would train with this formation and adapt to whatever weapons they used with it. The Greeks used the dory and pikes or essentially any long spear to keep the enemy from getting near their shield-wall. Thus, the Greek Phalanx.
Saxons mainly used spears for medium-distance combat, but they also used short-hand weapons like swords (for the wealthy) and axes. In the show, many of them used the seax (yes, Saxons used the seax, too). The seax is practically a short-sword, which would be very useful inside of a shield wall, and not very difficult to use in the first two ranks. Spears would be useful for the initial moments in the engagement, but when there are a bunch of sweaty, hairy Danes striking at you and trying to stab or hack into the small holes in the wall, a short-sword would be much easier to use.
In conclusion, yes, I believe that in history, shield-walls could very well have been used this way. After all, one long line of enemies only a few shields thick wouldn't prove very well if they're past your spears and hacking your legs. I'd love to hear what others have to say, I just love to think of possibilities like this.