The Midrash comments that Pessah and the 9th of Av always fall on the same day of the week.

The Pesach of Egypt was not an ideal sacrifice. The true festival lay ahead, in the future, in Eretz Yisrael.  What was required of the nation in Egypt was a demonstration of faith in that future despite the difficult conditions that existed in Egypt. The combination of the maror and the Pesach declares that faith in the future is victorious over the depression of the present; it is indeed possible to taste the redemption in the very grains of the maror.

Eating maror in the Beit HaMikdash was meant to help us identify with the heroic faith of our forefathers in Egypt, which attained its justification and its realization in the celebration of the Pessah in the Mikdash.  But after the Beit Hamikdah was destroyed, the grand celebration of Pessah appears to have been a passing euphoria; the Pessah of Egypt - observance of the mitzvot under difficult conditions - became the dominant situation for all generations.  For the weary nation of Israel only absolute redemption can justify the old understanding of Pesach in Egypt - as a road-sign for the future.  At this stage the Pesach of Egypt appears as nothing more than yet another example of the gloomy scenario which plays itself over and over - a perverted observance of the beautiful Torah which exists only in the dreams of seers.  The maror was supposed to be the basis for the Pessah sacrifice, but Tish'a be-Av gives it a new perspective: the sacrifice has disappeared, but the maror remains.

 

Courtesy of the Virtual Beit Midrash, Yeshivat Har Etzion