Modern scholars in Bengal are divided in their opinion
The statements of Minhaj and Island cannot be altogether disproved. Their statements can neither be described as exaggeration in the context of the prevailing conditions nor can they prove at the same time Lakshrnansena's cowardice. Still a question may arise as to why Lakshmansena could do nothing to resist the invaders although in the past he gave much proof of his valour and military prowess on several occasions by conquering Benaras, Kalinga and Kamrupa. The easy victory of Bakhtyar and the flight of Lakshmansena require a critical assessment of the whole episode. The whole issue may be discussed in the following way to arrive at a correct conclusion.
Modern scholars are divided in their opinion as to whether Nadia or Navadwipa was the official capital of the Sena Dynasty. It is admitted by all that Raja Lakshmansena, in his old age, had been residing in Nadia on the bank of the holy Ganges. "There is no evidence that Nadia was ever the permanent capital of the Sena Kings". Lakshmansena was deeply attached to Brahmanical religion and hence he considered it an act of piety to live close to the Ganges out of regard for its sanctity. With the coming of the Sena King to Nadia, pious people as well as wealthy people and the officials took up their residence on the bank of the Ganges. As a result, a city gradually grew up on both the banks of the river. However, there was neither any protective wall nor any fort to defend the city against any foreign invasion. Neither Minhaj nor Isami has referred to any protective wall of bricks. Probably a fence of pointed stakes encircled the main part of the city. "The place (of Lakshmansena) as we know, stood on the very bank of the Ganges, while the city's western gate must have been far inland inorder to intercept the merchandise that came from the south and the west by the land route, so that the custom duty could be collected here".
Internal condition as well as its defensive arrangements of Bengal
From the Western side, access to Bengal was much easier through Oudh Tirhut across the Gandak and Kosi rivers trailing along the northen bank of the Ganges or through the narrow Teliagarhi pass near Rajmahal. Throughout this long route, there is no physical barrier of any kind. To the south of the Telingarhi pass lay a land of dense forests and hills known as Jharkand, through which no large army could march due to the absence of roads and human habitations. "Only small select bodies of hardy cavalry mounted on superb horses could make a dash across this terra incognita, if they were guided by local zamindars." Hence it would be reasonable to suppose that the Sena King posted his defensive forces at the strategic Teliagarhi pass to intercept any invading army from the west and took no measure to defend the temporary capital city of Nadia either by raising defensive walls or garrisoning his troops there. Raja Lakshmansena could never imagine that any foreign army by-passing the Teliagarhi pass, would ever venture to enter Bengal through the hills and forests of Jhar-khand.
Hence he never thought fit expedient to ortify Nadia. Muhammad Bakhtyar preferred this difficult and unusual route to avoid the ready-army of the Hindu Raja at Telingarhi so as to surprise the latter at Nadia. There was nothing half-hazard in the plan of Bakhtyar which was well calculated and well executed. He was not only daring but also shrewd. Long before his match upon Nadia, he collected necessary information about the internal condition of Bengal as well as its defensive arrangements. The fact that Bakhtyar's easy entry into the city of Nadia with a small number of followers in the disguise of horse- dealers without exciting the curiosity of the people there is a positive evidence that Turkish horse-dealers visited Nadia before and possibly spied out the defensive arrangements of the city. Only when Bakhtyar became convinced that there was no possibility of any armed resistance from the side of the Hindu Raja that he ventured upon that risk with a small body of picked cavalry. And so Bakhtyar did not lead his army through the normal route of the Teliagarhi pass or made an attempt upon the fortified capital city of Gaur before capturing Nadia. Starting from Bihar Sarif, Bakhtyar left the Ganges "on his left bank at Teliagarhi and proceeding southwardly direction through Jharkhand and marching across the river Ajay, entered Nadia. Defenceless as he was, Lakshmansena was overwhelmed by the attack of a regular army and hence he had no other alternative than to take to flight for safety. Possibly the Raja had to flee for fear of being oppressed at the hands of the Yavanas.
Muhammadan conquest of Western and Northern Bengal
A staunch follower of Brahmanical religion, he was afraid of forceful conversion by the invaders. "By a combination of strategem, military skill and adroitness. Bakhtyar conquered Nadia and unfurled the banner of Islam". The fact that Nadia was the capital of Lakshmansena is not supported by any reliable authority. Abid Ali Khan writes, "Gaur, under the name of Ratnavati and Lakshanavati was probably one of the royal capitals of the Pal and Sen kings, but its recorded history does not begin until the Muhammadan conquest of Western and Northern Bengal by Muhammad-i-Bakhtyar Khalji… Lakshman Sen escaped first possibly to his other capital at Lakshmanavati and then to Sunargaon in Eastern Bengal..." The statement of Minhaj that "when his (Bakhtyar's) army arrived, the whole city (Nadia) was brought under subjection and he fixed his headquarters there" does not seem to be wholly correct. It is true, of course, that with the arrival of his army the city of Nadia was brought under subjection but he never fixed his headquarters there as Abid Ali Khan writes "Muhammed Bakhtyar followed him (Lakshmansena) as far as Lakshmanavati which was then established as the chief seat of Muhammadan power in Bengal and is henceforward known by a shortened form of the old name viz. Lakhnauti".