that is true, but coming from thailand all the way down to sg has already drained the soldiers in terms of resources, both mentally and physically in such a rush period. anyway those guns are you were saying if i do not recall wrongly its for navel battle. that itself is another joke
losing the war due to underestimating the jap plays a very heavy role. but wrong ground judgement of the enemy and lack of intelligence on it was another serious factor which many overlooked. situation was really bad for the japanese troop then even though they had already enter singapore in a lightning fast amazing speed. they were really putting on a very strong false front. if you were to read the account and dairy of the japanese commander, he fear going to the war all out to the street when he reach singapore. i would say the most important factor that result in losing the war in singapore is the lousy management at the top, not able to coordinate the troops and get proper info and intel about the enemy.
"My attack on Singapore was a bluff – a bluff that worked. I had 30,000 men and was outnumbered more than three to one. I knew that if I had to fight for long for Singapore, I would be beaten. That is why the surrender had to be at once. I was very frightened all the time that the British would discover our numerical weakness and lack of supplies and force me into disastrous street fighting."
– Tomoyuki Yamashita Shores 1992, p. 383.
things were bad for the local troop then, but it was way much worse for the japanese. i did read on the account of general yamashita that he would most likely surrender if the war drag on for another 2 weeks.