Such is the simpler explanation of the way in which the last two missions came to be established. It has, however, been suggested that, while all this may be true as far as it goes, other causes were at work of a subtler character than those specified, and that these causes were involved in the development of political affairs. It will have been noted that, though the threatened encroachments of the Russians had been one of the chief reasons for this Spanish occupation of Alta California, there had hitherto been no attempt to meet their possible advances in the very regions where they were most to be expected--that is, in the country north of San Francisco. In course of time, however, always with the ostensible purpose of hunting the seal and the otter, the Russians were found to be creeping further and further south; and at length, under instructions from St. Petersburg, they took possession of the region of Bodega Bay, establishing there a trading post of their Fur Company, and a strong military station which they called Fort Ross. As this settlement was on the coast, and only sixty-five miles, as the crow flies, from San Francisco, it will be seen that the Spanish authorities had some genuine cause for alarm. And the mission movement north of San Francisco is considered by some writers to have been initiated, less from spiritual motives, than from the dread of continued Russian aggression, and the hope of raising at least a slight barrier against it. However this may be, the two missions were never employed for defensive purposes; nor is it very clear that they could have been made of much practical service in case of actual need. X. Such, in briefest outline, is the story of the planting of the twenty-one missions of Alta California. This story, as we have seen, brings us down to the year 1823. But by this time, as we follow the chronicles, our attention has already begun to be diverted from the forces which still made for growth and success to those which ere long were to co-operate for the complete undoing of the mission system and the ruin of all its work.