"Is it true that nobody had been able to capture Vimy previously?"

It should be remembered that at that time Canada was mostly rural, and rural males were of necessity outdoorsman. Much of their lives had consisted of doing hard, miserable work in the cold and damp. Most had only gone to school when there no pressing work to be done outdoors. Many of them were experienced hunters as well, so, many of these were men who had grown up using weapons and tools in the harshest conditions. In short, they were a rugged bunch. We wouldn't be able to mount as formidable a force of volunteers on such short notice today.