They are started by using the inertia of a spinning flywheel. You crank the flywheel up to speed with a hand crank once you have cranked it up to speed you remove the cranking handle, then engage a clutch which makes the flywheel turn the engine

On all German WW2 tanks they had the hand crank start-up along with normal battery start-up. The crew usually only used the hand crank method when it was cold outside and the batteries were too low on power to start the tank.

I saw a King Tiger tank at a museum in Germany. I was surprised at how big it was for a WWII era tank. The tracks were super wide and at 68 tons it was heavy!

I remember the Leopard 1 and its sideways exhaust. When passing by the barracks barely 1m away and at the same height as the windows of that building.

I lived 17 years of my life, never knowing real bliss....until I hit the "tac idle" switch on an Abrams tank. There's nothing quite like it

One of the reasons the M1A2 uses a gas turbine engine, is because it's quieter than a diesel. You can hear a diesel from a long way off, but the turbine is a lot harder to hear. It also provides a lot more power, at a much more steady rate