Alexander was allowed to transport a force of 30,000 foot and 4000 or 5000 horse from the Chersonese to Mysia without the slightest interference on the part of the enemy, notwithstanding that his naval power was weak and that of the Persians very considerable.

This is one of those pieces of remissness in the Persian conduct of military matters, whereof we have already had to note signal instances, and which constantly caused the failure of very elaborate and judicious preparations to meet a danger.
Great efforts had been made to collect and equip a numerous fleet, and a few weeks later it was all-powerful in the Egean.

But it was absent exactly at the time when it was wanted.

Alexander's passage and landing were unopposed, and the Persians thus admitted within the Empire without a struggle the enemy who was fated to destroy it.
When the Persian commanders heard that Alexander was in Asia, they were anxious to give him battle.

One alone, the Rhodian Greek, Memnon, proposed and urged a wholly different plan of operations.