A saw is definitely easier and more efficient for cutting lengths of wood down into fire-sized pieces from a length perspective (I use one of these). However, if there are logs supplied as the original post suggests, they may already be fine length wise. I find the saw is usually only needed when gathering firewood from the forest.

However, whether you need to cut the wood to length or not, you will likely need to split the wood; you need to start small with your fuel to get the fire going. You can do this with either with a hatchet or by batonning with an appropriate fixed blade knife (the latter is more controlled and, I think, less prone to injury for the uninitiated). However, this assumes the logs will be smaller, if they are a larger diameter then an axe may be needed to split them.

I recently came across the following graphic that explains making a fire well:


Source: Scoutmastercg

While this graphic describes gathering fuel of the appropriate sizes, the other method - especially if all you have are logs - is to process the logs into the various sizes with your knife and/or hatchet/axe.