After a stay of three to four months at Gaur, Humayun planned back to Agra, leaving a small garrison behind. In spite of having a series of problems such as the rainy season, discontent in the nobility, and the constant harrying attacks of the Afghans, Humayun managed to get his army back to Chausa near Buxar, without any serious loss.
As Kamran heard about Hindal’s act, he left Lahore to suppress Hindal’s rebellion at Agra. But Kamran, though not disloyal, made no attempt to send any help to Humayun.
Deceived by an offer of peace from Sher Shah, Humayun crossed to the eastern bank of the Karmnasa River and gave full opportunity to the Afghan horsemen encamped there. It was the great mistake of Humayun that reflected not only a bad political sense, but also a bad generalship as well.
Sher Shah’s forces attacked on Humayun surreptitiously; however, Humayun, somehow managed to escape from the battle field. He swam across the river with the help of a water-carrier. Sher Shah robbed Humayun’s treasures. In this war, about 7,000 Mughal soldiers and many prominent nobles were killed.
After the defeat at Chausa in March 1539, only the fullest unity among the Timurid princes and the nobles could have saved Humayun.
Kamran had a battle-hardened force of 10,000 Mughals under his command at Agra. But he had not come forward to help Humayun, probably, he had lost confidence in Humayun's leadership. On the other hand, Humayun was not ready to assign the command of the armies to Kamran, as he could misuse it to store power for himself. The confusions between the two brothers grew till Kamran decided to return back to Lahore with his army.
The army hastily assembled by Humayun at Agra was no match against Sher Shah. However, in May 1540, the battle of Kanauj was bitterly contested. Both the younger brothers of Humayun namely Askari and Hindal, fought courageously, but to no avail.
The battle of Kanauj taken away Humayun’s empire and he became a prince without a kingdom; Kabul and Qandhar remaining under Kamran. Sher Shah, now became the sole powerful ruler of north India.
Humayun kept wandering in Sindh and its neighboring countries for the next two and a half years, planning various schemes to regain his kingdom. But hardly anyone was ready to help him. Surprisingly, his own brothers were against him, and even had tried to kill or imprison him. Nevertheless, Humayun faced all these trials and tribulations with great fortitude and courage. The downfall period of Humayun reflected the best part of his character.
While wondering in search of shelter, Humayun reached at the court of the Iranian king. In 1545, with the help of Iranian king, Humayun recaptured Qandhar and Kabul.
Reasons of Humayun’s Downfall
The major reasons for Humayun's failure were −
Humayun’s inability to understand the nature of the Afghan power and Sher Shah’s deceptive trick.
The presence of large numbers of Afghan tribes across the north India and their nature of getting united under a capable leader (like Sher Shah).
Without getting the support of the local rulers and zamindars, the Mughals were bound to remain numerically inferior.
The differences of Humayun with his brothers, and his alleged faults of character.
Though Humayun was a competent general and politician, his two mistakes i.e. ill-conceived Bengal campaign and wrong interpretation of Sher Shah’s proposal made him lose.
Humayun's life was a romantic one, as he experienced from rich to rag and again from rag to rich.
In 1555, after the break-up of the Sher Shah’s empire, Humayun again recovered Delhi; however, he did not live long to enjoy his victory.
Humayun died because of fall from the first floor of the library building in his fort at Delhi.
The tomb of Humayun was built by the orders of Akbar (son of Humayun) and Humayun's first wife (Bega Begum). And, the tomb was designed by Mirak Mirza Ghiyas, a Persian architect appointed by Bega Begum.
Building of the tomb was started in 1565 (nine years after the death of Humayun) and completed in 1572. The total cost spent in the building (of tomb) was 1.5 million rupees (at the time).