That is why from WW2 lessons, we can summarise few points:
1) Air force very very important.
Jap planes are unchallenged after 24 hours of the 1st air raid.
They bomb the hell out of british command. Worst still, jap can
bomb the reserivor, power plant, supply depot, telephone station,
camps and hospitals anywhere they like. In this way, it detract the
recovery effort and send the british commanders busy hiding and
running, rather than focus on the war in Malaysia.
With control of air, Jap can use airforce to sink the 2 great
battleships and perform a Pearl Harbour for the US navy. It opened
another dimension for attacking your enemies.
2) Arty and Armour very important.
Art can shell and pin down your enemy in trenches, while u perform
the franking movement. It also destroy the morale of the enemies
troops.
Armour thrust is most effective against heavily fortified british
lines. More importantly, armour can act as mobile support gun for
infantry attacks, or hold off the high ground. Jap even managed to
squeeze their armour force through the dense SE Asia forestation
and give a pleasant surprise fopr our Ang Mo commander.
3) Communication, Logisitic and Standardization
Weapons and training of the field troops must be standardize to
every basic step of fighting. The troopers and commanders must
speak and understand a common language. The communication btw the
troops and commanders must be free and open at all time in the war,
so that the commanders could make the best decision and the
troopers could minimise the causalities in the conflicts.
Allied divisions and different army grouos should have standardised
equipments and training to impove on inter-operateability and
synergised - combined armed division concept or Air - Land warfare
concept.
4) Nation identity buiding
In WW2, only a fraction of allied troops fighting are locals. Thus,
the allied troops are not fighting as bravely as many expected. But
the Chinese Vol and malay regiments were much more brave and
delicated compare to their ang mo peers. Of course, Aust unit had
fought very bravely to the bitter end as well. If the local british
commander is determined to fight a Iraqi style of urban war with
Jap, the out come for the Invasion of Malaya would be entirely
different. At least, the Jap with limited supplies and exhausted
troops would be seriously challenged by the numerically superior
Allied troops in street fighting. The Jap armour, airforce and navy
advantages would be useless in close combant in build-up
area.
Maybe with luck, British carriers, that stopped in India for
modification, could be deployed against the jap in conjunction with
the Allied Fleets in SE Asia.