Ignoring the benefit of hindsight, what you would have done in the following situation;
Should you send messengers to those loyal Welsh princes(brothers Bleððyn and Rhiwallon, who were allowed to rule in North Wales after acknowledging Edward as their overlord and agreeing to pay tribute and supply troops when asked), who could have speeded a substantial armed retinue of men by horse to aid you? Maybe also at least have sent 'feeler's out to Malcolm Canmore of Scotland, and the Cornish- giving them false promises of land agreements, etc? Around 21st Sept 1066, you force-march a huge army northwards 190m- most of it being mounted housecarls and thegns for speed- to meet a massive invasion army led by a fearsome Viking warlord(Hardraada) and your own traitorous younger brother(Tostig).
Immediately after this gruelling but stunning victory in which your army had slaughtered about 90% of the Norse veteran warriors, you hear of William's landing(29th Sept), you leave 'your man' in the north- Merleswein- to act as sheriff in that region(as Edwin and Morcar's forces had been shattered at the battle of Fulford, and maybe your faith in their command and loyalty also?), before another exhausting fast 190m march south to London.
As you dash southwards down the 'great north road' to London with your surviving mounted thegns and housecarls to rest, regroup and make arrangements for the impending battle, you send messengers into the southern and western shires (and E.Anglia?)to again quickly raise another general fyrd.
Controversially(and going against your experienced and militarily capable character as a proven general and statesman during King Edward's and your own short reign) you impulsively ignore your brother Gyrth's prudent advice(and maybe also Leofwine's, Edith's and your mother Gytha's, as well as many senior commanders?). This might be because;
1. You are proud of your military heritage and also feel morally bound as Wessex earl & King, to save your kinfolk from the brutal and deliberate ravages of the newly-invaded Normans(hangings, rapes, mutilations and slaying of children etc), designed to taunt you into premature battle- as William well knew it would.
2. You couldn't know if William was getting reinforcements by sea & thus getting stronger each day- the Saxon Navy was still in London at this time, but refitting to soon sail again to cut him off.
3. You are supremely confident of crushing William by surprise, having done the same to the fearsome Norse warlord Harald Hardrada's professional army only 3wks before with stunning success. Three years before that, you had crushed the Welsh menace, King gruffydd ap Llewelyn too with equal success.
4. Quickly "bottling William up" within the [then] narrow, marshy confines of the Hastings peninsula, with the natural aid of the flanking dense woods, was crucial to annul his cavalry that you saw in action in 1064- If William 'broke out' with his cavalry then he could go anywhere! Or maybe you could allow him to do so whilst also then 'scorching the earth' between Hastings and London/Winchester whilst hitting the starving, marching Norman army hard with huge, fierce and co-ordinated Guerilla-style ambushes/pitched battles- ala Hereward and the 'Silvatici'- then melting into the local lands which they would know inside-out? Norman warhorses, dying from malnutrition, would have left William's v.weakened army dangerously exposed & almost certainly slaughtered. Containing and starving William's men - and crucially their horses- was the crux, you could sap the Norman strength by war of attrition whilst they lay idle in their bottleneck & cut off by sea behind them. William would have to surrender- time was on your side...
5. You note William's lack of an advance inland for three weeks and must have thought either;- William wasn't strong enough to attack London or engage your army in pitched battle? Maybe William wanted you to attack him on Hastings peninsula, protected by the terrain etc, maybe with strong communications with Normandy?
So you arrange a meeting point which is well known to all the local men, and maybe previously considered by you as a useful defensive hill in case of having to withdraw from any possible reversals of fortune further south if plans didn't succeed.
Having left orders for the weary fyrdsmen still trickling in from the north(incl.archers- and the many men from the shires) to follow on and meet you at the 'hoare apple tree', you order your navy to sail behind the invader's base and whilst you soon afterwards speed a further 60m south with a large mounted army to link up with the fyrdsmen near the dense Andredsweald.
However, you may have made this meeting point too near to the Norman camp seven miles away, and their scouts alert William(unlike the Norse three weeks before) who pre-empts your attack by himself marching north to meet you. You do indeed have to fight a defensive battle now, but all isn't lost.
Your adversary is a brutally tough, experienced and great general whom you saw in battle two years before, and whom you also know needs to bring you to battle very soon if his conquest is to succeed- and his men(many mercenaries) don't revolt, as many did in 1069/70. All you have to do is issue strict orders to your fyrdsmen to defend well, and wait for reinforcements to come in from England throughout the day- another few thousand fresh fyrdsmen and maybe earls Waltheof, Morcar & Edwin with any surviving thegns/housecarls...
