I'll copypasta a post I made earlier about WWI tanks:
As they were in WWI, tanks were not a decisive weapon. They were a useful adjunct to the increasingly sophisticated tactics.
They were incredibly fragile machines. Not only were they highly prone to mechanical failure, they struggled to cross boggy ground and would often get stuck in craters. For example, in the battle of Messines Road Ridge, the tanks couldn't get forward at all due to the heavy rainfall the night before. Note that this didn't stop the attack being a huge success - sophisticated infantry/artillery co-operation and careful planning being sufficient for a 'bite and hold' break-in operation.
Being very large and slow, they were easy targets for artillery and the armour was thin enough to be punctured by over-powered rifle rounds (at least until the Mk IV appeared in mind 1917).
What's more, they were absolutely dreadful to fight in. There was no separate engine compartment and no provision for fume extraction. Temperatures could exceed 40 degrees, carbon monoxide, petrol and cordite fumes would choke the crew, the noise was so extreme that the driver had to signal gear changes by hammering on the hull with a spanner. Crude armour plate was prone to spalling from small arms fire, so little flakes or paint and steel would fly off the hull. The crew had to wear a special helmet with goggles and chain mail face covering because if one of those flakes got in your eye or if you breathed it in, you would be in very severe discomfort indeed. Conditions in the tanks were so bad, crews often needed several days to recover themselves from a single days' action.
They were also hideously prone to fire. The British used specialist recovery crews to extract the charred corpses of the crew. They were forbidden to talk about their work to anyone else.
The availability rates for the battle of Amiens, 1918, tells its own story.
•August 8th, 1918: 414 available
•August 9th, 1918: 145 available
•August 10th, 1918: 85 available
•August 11th, 1918: 38 available
•August 12th, 1918: 6 available
That's an attrition rate of up to 80% to 85% per diem
Hope this helps!