On her home world of Charn Jadis was at war with her sister and it lasted three days. Both sides agreed not to use their magic and fought it hand to hand. Charn had many wars in the past and as Jadis said many a great king came up against the House of Charn and failed. I think Jadis was in every war that took place on Charn and used her magic and swords. Jadis was descended from Lilith and Samael as I posted in an earlier post, and would have been born immortal as would her sister have been. Jadis lost the battle to her sister and rather than be ruled by her Jadis spoke the Deplorable Word and destroyed all living things including her sister. This word Jadis learnt in secret and had to pay a high price to learn it. I think the price was that when she used it she lost her immortally and most of her magic once she left Charn. The word is so powerful that it can destroy even immortals which is why her sister died. Aslan also knew of the word but could not use it to kill Jadis as he would have destroyed Narnia as well, Jadis also could not use it in Narnia as she was trapped there with no means of escape like she had on Charn. If Jadis was able to leave Narnia she would have used the word.
Jadis was used to death and torture on Charn and she brought it to peaceful Narnia. After a 1000 years in the wastelands Jadis rebuilt up her magic by learning the Deep Magic and made a powerful weapon, her wand. In taking Narnia she did not need an army, her magic and wand was enough as she inherited her fathers fighting skills, as he once was Gods right hand warrior. In the book and film Jadis is portrayed as being a excellent swordswoman but some say she just wore you down with her strength and not with any sword skills, I disagree, Jadis on Charn would have been skilled in using swords and in Narnia with her wand she did not have to use the sword as much as she did in the past. Jadis was tall, seven feet and did have superhuman strength but so did the Narnians she was fighting. No one in Narnia could match her or get close to her due to her wand. The Narnians were probably defeated very quickly and had no choice but to give in and be ruled by her, they did try to revolt but Jadis ended that again single handed, the only time Jadis had an army was when she learnt that Aslan was back and was building up his army, Jadis then summoned up all the evil she could and as Lewis said some he could not mention or your parents would not let you read his book (LWW).
Jadis had Narnia under her thumb for 100 years and was the longest ruler of Narnia, her Winter spell and her wand was enough to keep them in line and she had her spies to help her inforce her laws. Jadis in battle also had other advantages over her enemies, she had very good eyesight and hearing and could hear anyone sneaking up on her long before they got near her that's why in the film she turned a butterfly into stone without even looking at it, she could hear its wings beating. Her height and strength combined with her quick reflexes made her unbeatable and also the fact she was immortal. Even without her wand Jadis was untouchable for when Edmund broke it she had to go back to hand to hand combat were she used another one of her weapons, her eyes. Jadis could overpower you with her eyes and at close quarters fighting she would use them with deadly results as no one could look Jadis in the eyes for long and had to look away or at the ground and then they were vulnerable to her attacks. Jadis in Narnia as in Charn was a warrior Queen used to fighting and the Narnians were no match for her. Threw out Narnian history no one from Prince Caspian, Miraz ect and probably even Aslan himself would not have been a match for Jadis, even though he jumped on her at the end of the battle but I think that's all he could do as he was saving Peter and as she was immortal all he could do was to banish her from Narnia as he had done before. I think Jadis had a part to play in the final battle and I will post a piece on this later.