Why had Mohammed to use his guile to escape from the Meccan plot to murder him, when there was an Allah to save him?

The Meccan Quraish aristocracy, looked upon this as a direct threat to their position and they plotted to murder Mohammed. But the cunning chap that he was, he got to hear of it and gave them the slip and escaped in the dead of the night to Yathrib (Medina). But the fact that he had to escape from his would be assassins in the dead of the night makes one wonder why Allah did not strike dead his assassins, rather than having him flee like a coward from Mecca!