But the best designed plans may be frustrated by unskilfulness or timidity in the execution; and it was here, if we may trust the author who alone gives us any detailed account of the campaign, that the weakness of Alexander's character showed itself.

The northern army successfully traversed Armenia, and, invading Media, proved itself in numerous small actions superior to the Persian force opposed to it, and was able to plunder and ravage the entire country at its pleasure.

The southern division crossed Mesopotamia in safety, and threatened to invade Persia Proper.

Had Alexander with the third and main division kept faith with the two secondary armies, had he marched briskly and combined his movements with theirs, the triumph of the Roman arms would have been assured.

But, either from personal timidity or from an amiable regard for the anxieties of his mother Mamsea, he hung back while his right and left wings made their advance, and so allowed the enemy to concentrate their efforts on these two isolated bodies.