Though he was not the Lord of Highgarden yet, Delphin Tyrell was quite ready to be one. He was, in fact, given most of the power by his father, and he had just called eleven thousand men and just under 50 Knights to Highgarden. He would need these men more as protection than for attacking, as he did not want to attack at all. Farther South, his men were holding off some of Dorne, as always. He disliked Dorne for this, the border was set, just accepted. We don't come over, so you should not either. That was his logic, at least.
The men would be arriving shortly, as would his new suit of armor. He was looking forward to both of these things, and he might even march. No, he would not march, but he would have to sooner or later. He would do so on Dorne if he could still protect Highgarden and Oldtown, but that was sadly an impossibility. Dorne had it easy in his mind. They were only able to be attacked through the marshes or through ships landing, he was surrounded by two enemies and a friend. Not a very favorable position, he believed.