I believe that throughout history, the Tsars felt threatened. They then reformed in order to stay in power, and to stay in for power alone. However, this mindset only had an effect when the Tsar's power was threatened. Nevertheless, I believe that to find the factors that had an effect on the Russian system of government, one must look for the reason why felt threatened. Here war was an important factor, however it was not the only factor. Otherwise reform would not have occurred without war. I believe that if these other aforementioned factors were important enough to cause political change, then they must rank alongside war in terms of importance.
However it was not "the locomotive of history". i Together with discontent in the populace, and its manifestations (strikes, revolutionary activity, and assassinations), I believe War invariably changed the Russian political system.
I believe war had an impact for several reasons.
Throughout the period described Russia took part in three wars, in which they were crushed. Firstly, when a country fails in war, some would see it as being a sign that the country is less advanced in general. Firstly, the realisation that one's country was backward and prone to invasion threatened the Tsar's power, which then induced political change. He realised that if something was not done to improve and modernise that external enemies could be more of a danger than internal ones.
I have chosen an example to illustrate this. After the 1854-6 Crimean War, Alexander II initiated the emancipation of the Serfs, the creation of the Zemstvos, the Dumas, and the independent judiciary. He was even compelled to consider relinquishing a sizeable proportion of his power to the populace, but died before being able to implement these ideas. This was as a direct result of...