بِسۡمِ ٱللهِ ٱلرَّحۡمَـٰنِ ٱلرَّحِيمِ
أَلَمۡ تَرَ كَيۡفَ فَعَلَ رَبُّكَ بِأَصۡحَـٰبِ ٱلۡفِيلِ (١) أَلَمۡ يَجۡعَلۡ كَيۡدَهُمۡ فِى تَضۡلِيلٍ۬ (٢) وَأَرۡسَلَ عَلَيۡہِمۡ طَيۡرًا أَبَابِيلَ (٣) تَرۡمِيهِم بِحِجَارَةٍ۬ مِّن سِجِّيلٍ۬ (٤) فَجَعَلَهُمۡ كَعَصۡفٍ۬ مَّأۡڪُولِۭ (٥)
In the name of Allah, the Beneficent, the Merciful
And He sent against them birds, in flocks,(3)
Striking them with stones of Sijjîl (baked clay).(4)
And He made them like (an empty field of) stalks (of which the corn has been eaten up by cattle). (5)
Abraha Al-Ashram was the governor of Yemen on behalf of the king of Ethiopia. He (Abrahah) thought to build a house (like the Kaabah at Makkah) in Sana (the capital of Yemen) and call the Arabs to perform the pilgrimage there in Sana instead of the Kaabah in Makkah, with the intention of diverting the trade and benefits from Makkah to Yemen. He presented his idea to the king of Ethiopia who agreed to it. So the house (church) was built and he named it Al-Qullais; there was no church of its like at that time.
When Abrahah Al-Ashram saw that, he could not control his anger and raised an army to invade Makkah and demolish the Kaabah. He had in that army thirteen elephants and amongst them was an elephant called Mahmud which was the biggest of them. So that army proceeded and none amongst the Arab tribes that faced them (fought against them) but was killed and defeated, till it approached near Makkah.
While the army was marching towards Makkah, in the middle of the valley, suddenly it was overtaken by flocks of birds, flocks after flocks, air-raiding that army with small stones slightly bigger than a lentil seed. There never fell a stone on a soldier except it dissolved his flesh and burst it into pieces. So they perished with a total destruction. Abrahah Al-Ashram fled away while his flesh was bursting into pieces till he died on the way (back to Yemen).
(Source: Extracted from Tafsir of Surah Al-Fil (Surah 105) by Ibn Kathir as found in Translation of the Noble Quran by Muhammad Muhsin Khan.)