Why did the Germans not back up the Bismarck?

the same with the Graft Spee German arrogance the nazis built what we called Pocket Battleships all 6 should have been in the Atlantic together

then we would have seen the USA really show its true Nazi Colours

Scharnhorst 26 December 1943), the Royal Navy battleship HMS Duke of York and her escorts sank Scharnhorst

Tirpitz 12 November 1944, British Lancaster bombers equipped with 12,000-pound (5,400 kg) "Tallboy" bombs scored two direct hits and a near miss which caused the ship to capsize rapidly.

Bizmark hit by torpedoes dropped by Swordfish the Steering gear out of action Scuttled by the Captain

Admira sheer moved to Kiel for repairs in March 1945, where she was Bombed and capsized by British bombers

none of them had a very distinguished career

Peter Gore Seer,

 Easy Peasy, The Yanks Supplied The Material And Funding, So It Cost Germany Nil.

"Been reading about the Bismarck, its fight in the North Sea and eventual sinking"

And none of that reading mentioned why it was alone when attacked (it hadn't been earlier in its sortie)?

Surely it at least didn't mention taking place in the North Sea, if it did you need to ask for your money back.

What you need to do is read about the Bismarck. Oh, wait....... you did......?!

The reason in quite prosaic. Communications and relations between the High Seas Fleet HQ and U-Boat HQ were hardly automatic. Then there was arrogance. bismark was only 300 miles from France and less than that for air cover when it was spotted by a Brit plane then attacked by torpedo boats working off a carrier. One of the torps disabled the rudder which left the ship steaming TOWARD England. the ship was doomed

There was support for the Bismark, During during Operation Rheinübung, the attempted breakout into the Atlantic the Bismark was accompanied by the heavy cruiser, Prinz Eugen and three destroyers. At the Battle of the Denmark Strait, the battlecruiser HMS Hood initially engaged Prinz Eugen, while HMS Prince of Wales engaged Bismarck. In the ensuing battle Hood was destroyed by the combined fire of Bismarck and Prinz Eugen, which then damaged Prince of Wales and forced her retreat. Bismarck suffered sufficient damage from three hits to force an end to the raiding mission.

U-boats would not have been able to keep up.  It did go out with another ship, the Prinz Eugen but it sustained damage in the battle with the Hood and Prince of Wales.

Because the vessel was so huge it was thought that it alone could destroy an entire fleet before that fleet came into their effective weapon's range.