Early on in their careers, Batman and Superman met each other during a case when they would attempt to protect each other from the danger posed by a gang of Kryptonite smugglers
Knowing that Jason was in good hands, Batman focused on uncovering Hill's conspiracy, which caused the Mayor to suspend Gordon from the GCPD, command the police to arrest Batman by any means necessary and shoot Bullock in cold blood.  Avoiding police capture, Batman started looking for the Night-Slayer and he finally confronted the killer in Nocturna's apartment, where the struggle ended with the death of Doctor Fang and Batman assuming he is responsible for the death when in fact, it was the Night-Slayer who murdered the crook and made Batman believe otherwise.  For four days, Bruce meditated to recover his memory and sense of identity  and when he was ready, he learned that the Night-Slayer had used the Batman identity to commit crimes. Using all his resources, Batman unmasked the criminal to the public eye, clearing his own name and at the same moment, exposing Mayor Hill's corrupt management.  In the aftermath, Bruce finally got the official adoption of Jason. 
World's Finestinstallment loans Iowa
This would end with the Dynamic Duo and Superman working together for the first time to stop the gang.  Soon, Batman and Superman learned each other's secret identities, but promised to keep them a secret and they subsequently started working on several cases together.   When Superman rescued Batman and Robin from a mob attack, he would accidentally reveal his secret identity to Lois Lane, prompting Batman and Robin help stage an elaborate hoax in order to once more protect Superman's identity.  When Clark Kent and Lois Lane were captured by criminals who used heavy artillery in their crimes, Batman and Robin were led to their hideout thanks to Superman's secret aid and they captured the thugs.  Sometime later, Batman and Superman came up with an elaborate hoax wherein Batman poses as a swami and needs Superman's assistance in order to capture a group of crooks.  When Batman was exposed to a lethal gas by the Purple Mask Mob that would've killed the Dark Knight should he be physically active, Superman and Robin made Batman believe that he had a broken leg to keep him out of action until the poison wore off. 
Batman and Superman started a competition to define in which of their cities a science convention should be held, but the heroes were equal and the science convention took place on both cities.  Batman and Superman worked together to stop the evil Professor Pender, who used a machine to swap powers between them. Using their respective abilities, Super-Batman and Normal Superman managed to defeat Pender and return to their normal forms.  Next, Superman summons Batman and Robin to Metropolis to try and figure out who is trying to reveal Superman's secret identity. This all turns out to be a ruse to keep the Dynamic Duo preoccupied while Superman travels out to Gotham City to capture the Varrel Mob.  Superman and Batman stopped the Mole Gang, while also working on their civilian identities as temporary reporters in order to report the epic gang battle and save the Gotham Gazette from bankruptcy. 
When Superman went missing, Batman and Robin were asked to track down the Man of Steel and help him expose yet another empty threat from a criminal attempting to reveal Superman's secret identity. This case would bring the earliest meeting between Bruce Wayne and Clark Kent.  Sometime later, Batman and Superman investigated the mysterious case of the deaths of Robin and Jimmy Olsen, learned about a purposeful deception and captured an important gang in the process.  After this, they confronted the menace of the Composite Superman, who vanished away after creating serious havoc.  Next, the Batman and Superman team almost disappeared as a grudge grew between the heroes, but after working together to save Kandor, they moved past their disagreements.  Following this, the heroes stopped the double threat of Braniac and Clayface with help from their sidekicks Robin and Jimmy.  Batman and Superman later pulled a hoax on Doctor Zodiac, a notorious con-artist and captured him along with several other gangsters.  Eventually, the Composite Superman made a comeback, and he almost defeated the heroes. However, he sacrificed himself to prevent another alien from killing them and afterwards, Batman and Superman created a memorial in honor of Joseph Meach.  Some time later, Batman and Superman worked together to stop Dr. Light from killing Superman with a magical staff he had created.