Was it too cold for my old diesel?

I wanted to drive my camper to work today, because I'm going to need it in the evening. The temperature outside was +4°C (39 F, shown on a thermometer outside my window). So I thought that the engine will start with no trouble. I heard a lot about how old diesels wouldn't work in winter, because their compression is too low for the diesel fuel to ignite when injected. But I though that if the temperature was above freezing point, the engine will work.

But it tricked me. It didn't start. The glow plugs were lit (well... at least the glowplug indicator light was litten. The started did run, but the engine didn't start. During first trial I heard one or two explosions in the engine, but later on nothing happened. So I drove to work by bus.