((Alright. I was highly surprised when I saw this post - and even more surprised when Gira actually PM'd me asking for my input on the subject. So, I've got to say - it's excellent for where you are in your roleplaying experience. I wasn't writing nearly at this level when I had first started - or, at least, first taken interest. Read some of my old, old posts on Cerantia: A History for a bit of a reference - they sucked in more ways then one.
Regardless, there is always room for improvement. I would like to point out that it took quite some effort to actually think of something 'negative' to say - and this isn't really meant to be negative, but more like things that could be done better in the future. Take it as constructive criticism - and I ask that any and all do the same for my works.
Although I do see how you wrote this strictly from your character's point of view, it leaves many of his personal questions unanswered. This is relatively uncommon for something that is "in [his] own privacy of this bound book" - he can say anything he wants, yet he seems to only write about the political and militaristic occurrences of his day and age. There is no mention of his personal life, wife (or lack thereof), family, pets, in-depth personal views on the situation, and the like. I say in-depth personal views because, although he states that he clearly views the recent actions of the Emperor in a poor light, and although he does not like the newer members of the military that are based off of the militia, he does not offer input on how he would rather have it done. This could be a fault of the character, as it is in everyday life - it is far easier to find problems than solutions - yet I think that this is a man of action, as well as knowledge, and that it would fit well with his character to ponder on how he would do things if he was in power. There is also no mention of the mundane, little things in life - such as how he despises what he just had to eat before he wrote, or how his sword arm is aching from the last battle.
Yet despite all of these things, this is an excellent, far-above average post for an 'introductory' backstory post. It specifically leaves room for inclusion of the missing pages of the diary, and ends as if the character had to leave quickly to avoid the wrath of the Emperor due to the character taking action against the enemy. There is also a very consistent writing pattern that suggests a view of character-specific arrogance, superiority, and keen militaristic intellect.
My only suggestion for future posts is this: More is better. People will look and say TL

R, but for people like me, we will sit and read for hours if the backstory is good enough. And this is far better than good enough, in my honest opinion. Be sure to keep the writing style of your character intact (For example: Crazy commonly writes in short messages, and oftentimes takes extremes in his actions, and writes 'matter-of-factly'; Cerce writes in a fashion similar to a political theorist, and uses words repeatedly, such as 'Indeed; With firm resolve; However;' and can often be seen to write almost in a show-offy way.) I look forward to seeing more from you, Gira.

))
"One can concentrate so closely on the words of a sentence that one thereby misses the meaning. As can happen in any area of life. You must never lose focus on the larger landscape."