BIOGRAPHY
Dennis W. Dunphy grew up in Detroit, Michigan. He excelled at football in high school and college, planning to go pro once he graduated. This didn’t work out, though, as Dennis tried out for several NFL teams and ultimately didn’t make the cut. Dennis wasn’t willing to quit and he hit the gym in order to get stronger and tougher for next season’s tryouts. He was approached by a representative of the Power Broker with a treatment that would phenomenally increase his strength. The Power Broker process had risks, with reportedly only half of the recipients being success stories, but they said Dennis only had to pay if it worked.
Dennis’s process was a success, with his already impressive muscle mass increasing dramatically. The Power Broker informed him he would need to take regular doses of pills to stabilize the process and ensure there were no side effects. The treatment was highly expensive, and the Power Broker offered a job placement program to ensure the regular payment schedule was met. Dennis rejected the program at first, because he still dreamed of playing football. At tryouts, however, Dennis tragically realized just how strong he had become, when he caused a football to explode just by kicking it. Dennis saw a very real chance that he would seriously injure or possibly kill a normal football player with even a legal hit or tackle, and he knew he couldn’t play football anymore. [Captain America (1st series) #328]
Fortunately, there were other opportunities for sportsmanship. The Power Broker helped finance a new, Unlimited Class Wrestling Federation, deliberately built around contenders with superhuman strength. Applicants had to be able to straight lift more than one ton before being allowed to join. Dennis leaned into the colorful showmanship expected from the federation and stylized himself as “Demolition” Dunphy. Federation tryouts had a celebrity guest with Benjamin J. Grimm, the Thing, on leave from the Fantastic Four and looking to make a name for himself solo. The Thing was by far the physically strongest of the UCWF applicants, but Demolition Dunphy put on a good show trying to match his weightlifting limit.
Once the Unlimited Class Wrestling Federation was in business, the owner Ed Garner congratulated his dozen contenders and prepared to set up the first match, Demolition Dunphy vs. the Thing. Garner spoke to “Demo” privately and offered him a cash incentive to throw the match. He thought his audience expected the Thing to win and didn’t want to disappoint them. Demo refused Garner’s money and Grimm’s manager, Vance Astrovik, also overheard the exchange, sending the Thing in to confront the owner. Garner wasn’t genuinely corrupt, just desperate for his federation to succeed, so Ben set him straight that the UCWF was going to be above board the whole way. Demolition Dunphy and the Thing earned each other’s respect with the way they handled Garner together, and they went into the ring that night with their heads held high. It was a hard-fought match, but Ben Grimm beat Demolition Dunphy in a fair fight. [Thing (1st series) #28]
Demo and the Thing became good buddies, often sparring together during training. Dunphy also gave Ben some relationship advice when he was coming on too strong with Sharon Ventura. When Sharon was offered a place in the UCWF’s female division and a meeting with the Power Broker, Ben got overly curious. Sharon had an episode and escaped during the first portion of the Power Broker process, running into Ben who followed her. It turned out the second part of the process was only necessary to make the recipients dependent on the Broker’s “stabilizer pills,” keeping them under his control. 
The Power Broker now saw Ben and Sharon as threats to his organization, so he ordered clients to hunt them down or else he would withhold the stabilizer pills keeping their enhanced physiques from killing them.
After Ben and Sharon waded through the various wrestlers, Ben found Dunphy in the bathroom going through extreme withdrawal symptoms. Demo got the same order as the rest of the UCWF, but he refused to do anything that would hurt his friends. Ben called emergency services for his buddy while he and Sharon went after the Power Broker. The Broker had already cleared out his shop, however, and Ben was going through his own mutation problems. Sharon got him to the hospital in the room right next to Dunphy. Mercifully, it seemed that the Power Broker lied that the stabilizer pills were keeping his wrestlers alive. They were addictive but, once the pills were flushed from his system and Dunphy got through the withdrawal, the doctors believed he would make a full recovery. Ben’s problems were much worse, though, and he ended up leaving the hospital before Dunphy recovered. [Thing (1st series) #33-36]
The Power Broker went underground and cut ties to the UCWF after the Thing’s intrusion, and Edward Garner used all his resources to keep the scandal qu
iet so the federation could continue. After a few months, Captain America came out to California on a lead regarding some men he believed went through the same strength augmentation process, the Super-Patriot and his Bold Urban Commandos. Demo was thrilled to meet Cap and acted as his tour guide, sharing everything he knew about the Power Broker. When the UCWF looked like a dead end, Cap was ready to move on in his investigation. Dunphy had a score to settle with the Power Broker and asked to continue helping Cap with his mission. Given that Dennis was powered, trained in fighting already and quite likeable, Cap agreed.
Dennis was eager to fill the role of Captain America’s partner, even if it was only temporary. He had the league’s costumer whip up a masked costume for him as Demolition Man. After several days chasing leads, Cap and D-Man found the new front to the Power Broker’s business. 
Cap went in alone at first, posing as a potential customer, but he aroused suspicions and was captured. After a previously agreed thirty minutes, D-Man grabbed Cap’s shield and bashed his way through the front door. Dunphy managed to overpower the Broker’s super-strong guards, Bludgeon and Mangler, before breaking Cap free. The Power Broker’s chief scientist, Dr. Karl Malus, was apprehended. [Captain America (1st series) #328]