The Indian Army grew from about 200,000 in 1939 to over two and a half million by 1945, the largest volunteer force in history. Punjab supplied the largest single share.
Punjabi units fought in North Africa, at Keren in Eritrea, at Monte Cassino in Italy, in the Burma campaign at Kohima and Imphal, which are in India's north-east, and in Malaya, where a large number were taken prisoner at Singapore in 1942.
Those prisoners were the recruiting pool for the Indian National Army. Punjabis served on both sides of that division and in some cases in the same family.
The Bengal famine of 1943, in which between two and three million died, was in part a consequence of wartime procurement and transport policy, and Punjab's grain surplus was central to the supply system that failed elsewhere.
Demobilisation in 1946 and 1947 put hundreds of thousands of trained men back into Punjab villages months before the partition violence began. That is a fact several historians have pointed to and none has been able to weigh precisely.
Recruitment was run through the districts by quota, with deputy commissioners, zaildars and lambardars given targets, and the Rawalpindi, Jhelum and Attock districts on the western side carried the heaviest of them.
The Punjab regiments were rebuilt several times over. A battalion destroyed in one theatre was reconstituted out of the same recruiting area and sent out again, which is why a single district's casualty list can run through three separate campaigns.
The war put money into Punjabi villages on a scale nothing had before, and it put a generation of trained men back into them in 1946, a year before the province was divided.