"Of course, I am angry with you. For most of my life, you have either manipulated me, humiliated me or used me..." Aethelwulf lamented to his father when the Great Heathen Army invaded Wessex. Aethelwulf was the biggest victim of Ecbert's shrewdness and mistakes. Ecbert missed Ragnar's final trick of sending Ivar home with the instructions to bring hell on all of England, including Wessex.
On the brighter side, King Ecbert understood that England would have to learn to live with the Vikings at one point, and so he handled them better than King Aelle. However, despite his intelligence, the old king still made lots of mistakes that Wessex ended up paying for after his death.
Best: Taking Time To Study The Vikings
King Aelle lost his first battle against the Vikings because he never tried to understand them first. Ecbert did exactly the opposite; inviting the Vikings to his court and negotiating a peaceful solution with them. He understood that going to war against the combined force of Ragnar and King Horik would have destroyed his forces and probably taken over Wessex after a few battles.
His decision allowed him to turn the situation to his advantage as he managed to use the Vikings to defeat the uprising in Mercia. When the time came, he went back on his word and killed the Vikings to please his people as he had always planned.
Worst: Killing Kwenthrith
Compassion is the one thing that Ecbert never showed Kwenthrith. The poor princess had been hurt by everyone in her life, including her own brother. When Ecbert offered to be the father figure and help her, he didn't really follow through. Freeing her from Mercia only to turn her into a prisoner in his own court was the worst torture the queen of Mercia could imagine.
She was no longer a threat to Ecbert, so Ecbert should have let her go when she decided to escape. Killing her made Aethelwulf hate him even more while Magnus declared Ecbert's family his eternal enemies.
Best: Becoming Friends With Ragnar
Ecbert was the first opponent to outwit Ragnar and defeat him without going to war with him. King Horik, Rollo, and Floki were all pressuring Ragnar to kill as many Saxons as he could until Ecbert invited Ragnar to his castle and fooled him with a fake arrangement for peace. Ragnar and Ecbert formed a strange type of friendship.
They didn't trust each other, but they understood one another well enough to anticipate each other's intentions and next moves. Ragnar had a stronger army and could have beaten Ecbert easily if they went to war, so Ecbert was wise to give him the piece of land. The short-lived friendship prevented the Vikings from attacking Wessex again because Ragnar could now focus on raiding other places.
Worst: Killing The Viking Settlers
The Viking settlement was a win for the Ragnar, but it was also perfect insurance for the Saxons. The Vikings would never have attacked Wessex as long as the settlement lasted. The temporary squabbles between farmers could have been solved without a massacre. When Ecbert indirectly ordered the massacre of the settlement, he also created an eternal enemy of the Vikings.
When the Great Heathen Army came to avenge Ragnar's death, they used the massacre as another excuse to distrust Ecbert and his family and chose to massacre more Saxons in return. He also made it harder for his son and grandson to make peace with future Viking invaders.
Best: Protecting Athelstan
Ecbert's curiosity was another gif that he used to bring lots of good to Wessex. Every Christian in Wessex was in favor of killing the monk who had turned on his god and became a Viking, but Ecbert knew better.
He saved the young monk from being crucified and decided to put his knowledge of Latin to good use. In the process, he got new ways to strengthen Wessex's defenses and as a gate pass to negotiating with Ragnar Lothbrok. Athelstan also fathered Alfred, the best option for an heir that Ecbert got in the end.
Worst: Mistreating Aethelwulf
Aethelwulf was a good fighter, but he made a terrible king. Aethelwulf's failures could be traced back to his father, who never gave him a chance to gain actual leadership experience. He never learned anything good from Ecbert. All he did was hate his father for using him as a puppet, taking his wife then sending him to Rome so he could kill Kwenthrith and take over Mercia.
Aethelwulf didn't know what to do when he was finally made king. He refused to negotiate with the level-minded Ubbe, choosing to continue fighting with Ivar, which was catastrophic for the Saxons. If Ecbert had treated Aethelwulf better and taught him how to lead, things would have turned out differently.
Best: Choosing Alfred As His Heir
Ecbert liked Alfred from the time he was born because the little boy was smart and curious, just like his father. Aethelred was Aethelwulf's firstborn son; therefore, the obvious choice for an heir, but Ecbert knew better.
He understood that Wessex would need knowledge over muscle to defeat the Vikings in the long-term, and Alfred was just the person to accomplish that. Judith understood Ecbert's decision and decided to enforce it, although poisoning Aethelred was extreme of her.
Worst: Handing Ragnar To Aelle
When Ragnar came to England with his son and no army, Ecbert knew he had lost everything and that he had come to seek his death. Alfred being a wise king, should have saved the poor man. A living Ragnar in England would have given Ecbert the opportunity to understand the Vikings better and probably strengthen his defenses.
If he didn't want to kill him, he could still have sent him away peacefully to spare Wessex the wrath of the Great Heathen Army. He chose to continue with his shrewdness by handing him over to Aelle to face a painful death, not knowing he had fallen into Ragnar's trap. When the sons of Ragnar came to avenge their father, they sacked Wessex and Northumbria equally.
Best: Sacrificing Himself For Wessex
Ecbert had one last play when Ragnar's sons invaded, and it worked perfectly. It prevented the Vikings from overrunning Wessex and probably wiping out his bloodline after they invaded Northumbria. It was the first time that Aethelwulf was proud of his father.
He saved his family and the rest of the people of Wessex and handed over the crown leaving Ragnar's sons with nothing. It was selfless of the king who was always known to take care of his own interests first. Handing over the land to the Vikings under pressure would have meant the end of Wessex.
Worst: Allowing Ivar To Live
Ivar was a disaster to both the Vikings and the Saxons. He caused more trouble than the wars between the two communities had done all those years. All that could have been prevented if Ecbert had just killed him or held him as a prisoner after Ragnar's death.
Ecbert knew that Ragnar's message to the young Ivar was not good for the Saxons and that nothing good could come from the vengeance of Ragnar's sons, but he chose to save the boy anyway. It was his final gift to Ragnar Lothbrok, but it ended up hurting everyone more than anything Ecbert could have wished for.