In his most notable lightsaber duel against Anakin Skywalker, General Obi-Wan Kenobi achieves a position of elevation shouting, "It's over Anakin! I have the high ground." He follows up by using his height to his advantage, thereby defeating his previous apprentice. This is likely the first time fans notice the importance of the high ground in General Kenobi's battle strategy, but upon closer inspection, we see that taking the high ground in this battle is the culmination of all his previous victories in lightsaber duels.
Beginning in Star Wars Episode One: The Phantom Menace, Obi-Wan's first experience with the high ground comes at a time where he himself is on the low ground. After his master is killed by Darth Maul, Obi-Wan is kicked over a ledge to what most would perceive as a disadvantage. However, recognizing the existence of the high ground, Obi-Wan leaps back over the ledge effectively slicing through Darth Maal's hips, causing him to plummet into darkness.
Moving onto his next lightsaber battle, Obi-Wan and Anakin duel Count Dooku in Star Wars Episode Two: Attack of the Clones. Here, there is no high ground at any point in the battle, resulting in his first defeat. Fortunately, he is rescued by Master Yoda, allowing him to live on to his next battle.
To begin Star Wars Episode Three: Revenge of the Sith, Obi-Wan and Anakin rematch Count Dooku. Despite Anakin defeating Count Dooku, there is no high ground in this battle either, resulting in the unconsciousness of Obi-Wan.
At this point, Star Wars fans have seen Obi-Wan take part in three lightsaber battles, with the only victory coming from the battle with the presence of the high ground.
Next, we see Obi-Wan battle General Grievous in Star Wars Episode Three: Revenge of the Sith. In the first part of the battle, no high ground exists allowing General Grievous to narrowly escape death. However, General Kenobi is able to catch up to General Grievous before he makes it out of Utapau. This brings us to the second part of their confrontation where Obi-Wan is knocked over a ledge to the low ground. Recognizing the advantage due to his previous encounter with Darth Maul, he quickly uses the force to retrieve the blaster used to defeat General Grievous once and for all.
Obi-Wan wins his next lightsaber battle against his former apprentice Anakin Skywalker, now known as Darth Vader. This epic battle concludes with General Kenobi taking the high ground, allowing him to severe all of Anakin's remaining appendages, leaving him to burn near the lava.
At the end of Star Wars Episode Four: A New Hope, an elderly Obi-Wan Kenobi faces off against Darth Vader. Due to his age, Obi-Wan allows Darth Vader to win the battle so that he may take on more power to aid Luke Skywalker as a ghost of the force. However, we note that in this battle there is no high ground present, leading fans to believe that Obi-Wan's apparent surrender was due to the lack of physical high ground, not the moral high ground.
While the high ground seems to be of little importance to most Jedi, Obi-Wan makes this his strategy throughout the four films he appears in, indicating that the presence of the high ground is a mental state he uses to his advantage. If the high ground exists in the battle, Obi-Wan has it from a certain point of view.