Question 865: That's a damn order!

“‘Dig, boy,dig’”, shouted the Canadian engineer, Mr W L Lake, at his men as they watched elephants emerging out of the dense forest with ___ stains on their feet”. This is possibly the most distilled – though fanciful – version of the legend explaining the siting and naming of this place. Two events separated by seven years have become fused, but although neither is likely to be provable, such evidence that does exist appears sufficiently detailed to be credible.Various web sites offer variations on the elephant’s foot story, a consensus of which would be that engineers extending the Dibru-Sadiya railway line to Ledo for the Assam Railways and Trading Company (AR&TC) in 1882 were using elephants for haulage and noticed that the mud on one pachyderm’s feet smelled of ___. Retracing the trail of footprints, they found ___ seeping to the surface. One of the engineers, the Englishman (not Canadian) William Lake (aka "Willie Leova" Lake), was an ‘___ enthusiast’ and persuaded the company to do something that made this place economically important to India. What place? Fill in the blank too.

Answer: Digboi, oil