The recent fighting in Gaza was touted as something of a new age in urban warfare. Israel admitted that it used some new techniques, but in reality Israel mainly used a large array of tactics and techniques that it had developed, and used, over the last decade (and even earlier.)
Fighting inside cities has always been a rough business, especially for the attacker. Urban areas, which is what a lot of Gaza is, provide ample hiding places for the defender, and such battles often become an endless succession of ambushes for the attacker. World War II was full of bloody urban battles, and it was from this that another "rule of thumb" was developed. "To take a city, expect to lose at least one division worth of men (10-20,000 troops)." Urban battles in the half century since then have only confirmed the World War II experience.
But in the last decade, American and Israeli soldiers have found ways to use technological superiority and better tactics to defeat the advantages of the hidden defenders. Israel has proved that the new tactics worked, as it used them to defeat diehard Palestinian fighters in densely built towns and villages in the West Bank and Gaza. The most successful tactics feature several key elements, and all of them were used by both Israel and the United States in the West Bank and Iraq years before the recent 22 day campaign in Gaza.
Intelligence gathering, using UAVs and electronic eavesdropping are not new technologies. The difference is that there are now more UAVs and more powerful sensors available. These enable the attacker to get an idea of what the defender is doing in terms of preparations. Israel also used a lot of HUMINT (human intelligence) using Arab speaking agents and local informers. Getting HUMINT is a lot harder for most other armies, like the American troops in Iraq. But even here, you will find Iraqis who will help you because they hate the violence more than an invading army. Intelligence always pays off if you collect all the information you can. The more you know, the less you bleed. This is a simple rule that is always broken by armies that take a lot of casualties. Your information about the enemy controls everything else you do, so go get all you can, anyway you can, before you send your troops in.
Having a well thought plan for what you are going to do is essential. You have to be ready to be flexible, including pulling out quickly if your intelligence was not good enough and the enemy is getting the best of the fight. Israel was particularly good at this during the recent 22 day battle.
Warning the civilians to get out is an old Israeli technique. Most civilians will comply, many without being warned. You don't always have to attack an area where you have warned the civilians, but this unnerves the enemy troops anyway. Palestinian civilians knew of this old Israeli method, which was more effective recently because Israel has become better about grabbing control of local telephone systems, and getting phone numbers of specific targets.
It's always been important to come in from all sides, if possible, and from above. Putting snipers and assault teams on roofs via helicopters freaks out the enemy and does a lot to suppress or destroy his snipers. Come in at night, when your night-vision gear gives you advantage. Come in at 3 AM, when the enemy is not ready to rumble, and you are. Surprise saves lives. Move fast. American and Israeli troops are professionals, while their opponents usually are not, and this allows you to execute your plan faster than most of the enemy troops can react. Catch them sleeping, literally, if you can. As the minutes tick by, the enemy gradually get their act together. Don't let them. Israel did this in Gaza, while they did not in southern Lebanon in 2006.
Coming in on the ground means lots of tanks and engineering equipment. Most armies have older model tanks modified for engineering work (with a bulldozer blade and run by engineers who know how to quickly clear roadblocks, booby traps and mines.) Israeli and American forces also have the 62 ton D-9 armored (via an Israeli armor kit) for this kind of work. The Israelis, like the Americans, pioneered the use of special explosives to blast entry holes through walls, so troops can quickly get to their objectives. The D-9 lets you bash through buildings, or even shake the enemy out of some buildings. Israel used all of this in Gaza, as they had previously done in the West Bank.
Use lots of helicopters, but remember that the choppers have to keep moving to avoid taking fatal fire from the ground. The helicopter crews have night vision equipment as well, and can add cannon or missile fire, or more troops, to the right place when you really need it. The only difference in Gaza was that Israel had more AH-64 helicopter gunships and these choppers were under the control of the infantry brigade they were supporting. This small change in control made a big difference.
Predator UAVs can keep watching back alleys and other approaches for enemy activity. The U.S. uses AC-130 gunships, which can also see at night, and pile on a lot of firepower when needed. Snipers and enemy troops may be hidden, but they aren't bullet and bomb proof.
Tanks are good not because they have big guns, but because they are bulletproof, mobile and have machine-guns. You don't want to level the area with 120mm shells, because the rubble gets in your way and gives the enemy more hiding places. Israel also used, for the first time, older Merkava tanks, with the 20 ton turret removed, as armored infantry vehicles. There were a great success.
Keep monitoring the enemy's communications. If the enemy wants to reinforce some of their guys who are getting hammered, they will use radios or cell phones. Make sure you can intercept the message and foil their plans. The Israelis were better prepared to do this in Gaza, than they were in Lebanon in 2006.
Practice and rehearse before you go in. You can never get enough of this. Israel did not have enough of this in Lebanon, but had lots of it before going into Gaza.
All this pre-dawn Shock and Awe will get the enemies attention, and paralyze many of them. While they are frozen with fear or trying to figure out what to do next, go in and kill them. Coming down from the roof will be less likely to encounter booby traps, as these are usually placed at the ground floor entrances. Your intelligence should have shown you where all the exits are, so none of the enemy escape plans will work. This approach was a shock for the Hamas fighters, who never got their act together.
Finally, remember that often this kind of street fighting is the last thing you will have to do. As American and British troops have already demonstrated in Basra and Baghdad, a fast moving armored force, with air cover and good intelligence, can rapidly move into a city, destroy enemy headquarters, supply dumps and assembly areas, and get out before the bad guys can react. This is what Israel recently did in Gaza.
A lot depends on who you are fighting. Stalingrad, Mogadishu and Grozny are often invoked by pundits who forget that Baghdad and Gaza were defended by Arabs, not Russians, Somalis or Chechens. But we tend to forget that Stalingrad, Mogadishu and Grozny were not fought using the tactics and techniques mentioned above. How you do it, not who you are doing it to, has lot more to do with the outcome.
The Israelis have fought several urban battles using these tactics, and suffered the same low casualties the coalition forces took in the first two weeks of the Iraqi campaign. Street fighting doesn't mean a bloodbath, it does mean a lot more preparation and effort.