Why does he go to Basra? How long does he wait there, and why?
He goes to Basra to visit the Consulate-General to collect and answer his mail from Europe.
He waits there for several days because his mail had not arrived at the Consulate-General. While his friend's mail had already reached, his own mail was delayed, forcing him to stay in Basra until it arrived.
Explanation
The author travelled to Basra specifically to go to the Consulate-General to collect and respond to his European mail. However, upon arriving, he discovered that while his friend's mail was there, his own had not arrived yet. As a result, he had to wait for several days in Basra until his mail finally reached the Consulate-General.
Solution Steps
Step 1: Identify the reason for the visit to Basra from the text (to collect and answer mail at the Consulate-General).
Step 2: Determine the duration of the wait (several days, as 'The days passed peacefully at Basra').
Step 3: Identify the cause of the delay (his mail had not arrived at the Consulate-General).