- May 2014
What do you think is more likely--Britain conquering parts of Persia and letting Russia have the rest of Persia or Britain actually going to war with Russia over this issue?Well, there was a Russian-Persian war from 1826-28. In which Persia was goaded by Britain to regain lost territory from the earlier 1804-13 war. They lost badly and Russia gained the north Caucasus. So if the war happened in the late 1810's it would probably be pretty much the same, only the cause being different (if Russia started it).
Now if Russia invaded with the goal of total annexation of Persia, this gets more complicated. In the 1826-28 war Russia completely defeated Persia, even temporarily occupying Tabriz. If they kept pushing they probably could have conquered the whole country but logistically it would have been very difficult to maintain the supply lines across the whole area. This would necessitate the conquest of central asia to link up with the newly conquered Persia.
More importantly the other regional powers wouldn't sit idle while Russia devours huge chunks of territory. Britain already considered Russia its main rival and would work to prevent this annexation. Either by demanding Russia pull back (could be an earlier version of the Crimean war, only over the collapse of Persia), grabbing parts of Persia for themselves (Baluchistan and south), or by militarily intervening through proxies (ottoman empire and others).
Also, Russia can maintain supplies through the Caucasus, no? Or is that extremely difficult to do in the pre-railroad era? If so, I don't think that movement through Central Asia is actually going to be much easier due to its desert terrain.