Why has Edmund decided to escape, now? Why is now different than escaping when he was in Narnia before? Wouldn't it have been easier to escape then?
Well, back in Narnia, Peter was ready to help Edmund escape. He was ready to do what was necessary, but if Edmund disappeared while in Cair Paravel, it would cause a lot of trouble for the monarchs. There wouldn't have been an easy way for Edmund to escape on his own without coming across one of the Calormenes and, if Peter helped, they would risk Judas finding out and give another reason for war, which they were trying to prevent.
It is not legal for Narnians to buy slaves, so Peter could not purchase him. Slaves are supposed to remain with their masters until death or release, but, as you know, nothing can be done to punish the slave if he is never recaptured.
Well, why didn't he disappear, before, while in Narnia?
Edmund didn't believe himself to be Edmund anymore. He had lost any hope of ever returning to his home. He told himself he wasn't a king; he was a broken slave, like the ones in the tent in the last chapter. Any hope of escape had long since died, only restored to him, later, by Aslan, Himself.
Also, Edmund would not have Peter get too close to him. They could have sat together and discussed plans of escape, but if they failed, Edmund could be killed, leaving Peter more devastated than he was when Edmund was first lost. Edmund wouldn't have wanted to get Peter's hopes up in trying to free him, so he instead lowered his brother's hopes in trying to protect him from a greater hurt.
Aslan has told Edmund that He has a plan, so Edmund believes he is to be reunited. To him, there is no better chance at that than to attempt escape on his own.
Edmund took the first guard down with ease. He was paying no attention and was least expecting an attack from behind, like he should have been. Edmund had killed him quickly with a mere snap of the neck. The Calormene made no voice at all as he dropped dead to the ground.
Edmund took the scimitar and dagger from the soldier's sides. The dagger was tucked carefully into his rope belt, and he held the scimitar just like he used to hold his own sword.
It had been ages since he last possessed a weapon, but the hilt felt natural in the palm of his hand. It was like riding a bike: one could go on without riding for a great long while, but, once his feet are on the pedals once again, there's nothing to stop him from flying down the street. Of course, it had been years since Edmund had last rode his bike in Finchley, but he had heard that saying ("Just like riding a bike") enough times to believe it to be true.
He wouldn't have to believe for much longer, however, for he would soon find out for himself whether the the saying was true or not.
"You, boy!"
Edmund snapped his head toward the sound of a gruff Calormene voice. He froze up for a moment, unsure of what to do. Should he play dumb - act like he doesn't know what happened - or kill the man on the spot?
"You murdered this man!" The soldier said, gesturing to the the body - its neck twisted at a sickening angle - laying on the ground, between him and Edmund.
"I... I - uhh -" Edmund stuttered.
The soldier drew his sword. Edmund acted more out of instinct than anything. The moment the sword has been drawn, it was knocked from the Calormene's hand. In another instant, he lay dead, right beside the first man.
"Hey!"
Again, someone has caught Edmund's actions; but, this time, he did not freeze. As quickly as the man had dropped dead, Edmund had run from the scene. He could hear the sound of heavy foot-falls behind him and the shouts of more men as they noticed what was happening, but Edmund did not stop, he could not stop. He didn't even know for sure where he was headed, but he ran through the large encampment, nonetheless.
Edmund only stopped when his way was blocked by a large Calormene soldier. He turned to run back the other way, but there were two more men behind him.
The big man stepped closer and reached out to grab Edmund. He reacted in the only way he could think of: Edmund dove out of the man's reach, landing at the back of one of the many surrounding tents.
The soldier persisted. Edmund crawled backwards until his back was against the tent. He froze for one moment, an idea striking him. Just as the man's hand was about to close around the scruff of Edmund's tunic, the young king dropped further down, his full body against the dirt. He lifted the bottom hem of the tent and just barely squeezed his way under and inside.
Edmund wasted no time. He was immediately back on his feet, dashing out the tent flap and back through the camp.
More foot-falls, more shouting. Edmund could hardly pay attention, anymore. Every turn he took seemed to get him more and more lost in the maze of tents in the Calormene camp.
Finally, he turned a corner and came face to face with the nose of a light colored horse. The beast startled at its sudden guest, bucking up and nearly knocking Edmund off of his feet. Once he regained his balance, the king rushed to untie the horse which, he just now noticed, was only one in a line of about seven unsaddled horses, tied by the neck to some wooden posts hammered into the ground.
Edmund patted the horse to calm her nerves. "There, Girl. Just relax."
The horse took some deep breaths and, then, seemed to regulate her pattern. Edmund was about to mount when an arrow whizzed by, sticking itself in a barrel not one foot behind him.
Again the horse startled, but Edmund quickly got her under control. He would have liked to choose another horse, but the rest were far worse, bucking against their restraints and stomping the earth below them. This girl would have to do.
Edmund hopped onto her saddleless back and intertwined his fingers into her hair. He would be lucky if she ever followed his bidding. No matter, though; Edmund needed only for her to take him from the camp. He could find his own way to Peter from wherever this horse took him.
The Calormenes had just caught up to him, when Edmund kicked his heel into the horse's side. She surged forward, knocking two men to the ground and changing through the camp.
They had just passed the last of the tents when another arrow whizzed by, barely nicking Edmund on the cheek. His horse startled a little, but Edmund bent down and whispered comforts into her ear.
More arrows flew past, but none of them had been as close as the first one had been.
Edmund could feel the blood running down his face from the cut on his cheek, but he ignored the pain. As the arrows ceased to fly, Edmund's mind then drifted to his next task: finding Peter.