This is not about whether WWIII will happen or not or who will start it, this is a simple "What if?" scenario.

The reason i am asking this is because the internet Didn't exist in the first two world wars so there is nothing to look back at to see what would happen.

Personally i think that countries would block their enemy's IPs and simply deny them access to their websites.

Maybe a lot of bandwidth would be taken up for intelligence sharing/communications causing people's connections to be slower.

Everyone will [censored] about the government. Tumblr would make Satanic sacrifices to keep the war going or some [censored]. Pewdepie becomes one of those guys that talk like an idiot about the war and everyone listens and agrees with him. Soldiers will take a lot of selfies. FaceBook will explode with "If this gets a million likes, a soldier's life will be spared" spam. And trolling and flame wars will happen so often that servers would be hard to keep open.