U.S.-led warplanes and helicopters attacked Republican Guard units defending Baghdad on Monday while ground troops advanced to within 50 miles of the Iraqi capital. White House aides said a down payment on war-related costs would come to $75 billion.

Five days into Operation Iraqi Freedom, fierce resistance prevented American and British forces from securing the southern cities of Basra and An Nasiriyah and thwarted efforts to extinguish burning oil wells.

Iraq claimed custody, as well, of two American pilots after a helicopter went down, in addition to a handful of POWs taken over the weekend.

“These things are never easy,” British Prime Minister Tony Blair conceded Monday, the day his country suffered its first combat casualty of the war. “There will be some difficult times ahead but (the war)

is going to plan despite the tragedies.”

Saddam sought to rally his own country in a televised appearance. “Be patient, brothers, because God’s victory will be ours soon,” he said, appearing in full military garb and seeming more composed than in a taped appearance broadcast last week.

Despite Saddam’s defiant pose, a military barracks in the northern part of the country was bombed, and Baghdad fell under renewed air attack by day and by night. Iraqis set up mortar positions south of the city and piled sandbags around government buildings and other strategic locations, in evident anticipation of a battle to come.

“Coalition forces are closing in on Baghdad,” Maj. Gen. Stanley McChrystal told reporters at the Pentagon.

He said U.S. Apache helicopters attacked Saddam’s Republican Guard forces arrayed around Baghdad, while another official, speaking on condition of anonymity, said a “large portion” of the day’s bombing runs were dedicated to hitting the same units.

Asked about ground forces, McChrystal said, “We have not gotten into direct firefights with Republican Guard forces.”

That seemed a matter of not much time, though.

The Army’s 3rd Infantry Division was within 50 miles of the capital, battling sandstorms more than Iraqi fire as it neared the approaches to Baghdad.

Some Iraqis waved or gave a thumbs-up as the convoy passed on its dash through southern Iraq, while others stood stoically.

The advance of long columns of thousands of vehicles was aided by heavy air protection that wiped out a column of Iraqi armor at one point and sent some of Saddam’s outer defenses withdrawing toward the capital. The convoy passed bombed anti-aircraft guns, empty foxholes and berms dug for tanks that had been abandoned.

President Bush invited senior lawmakers to the White House, and aides said he would ask Congress for $75 billion. Of that, $62.6 billion would be in direct war costs, according to these aides, for 30 days of combat. The request was also expected to include up to $3 billion to guard against terrorist threats, as well as aid to Israel, Afghanistan and other U.S. allies, a down payment on humanitarian aid for Iraq and for rebuilding the country, and money to increase security for American diplomats.

Bush also talked with Russian President Vladimir Putin by phone. Spokesman Ari Fleischer said the president expressed concern about reports that Russia was selling anti-tank guided missiles, jamming devices and night-vision goggles to Baghdad.

In the world’s first war to be covered live on television, the news and images of American and British setbacks competed with pictures of battlefield successes.

Iraqi television showed pictures of one American helicopter in a grassy field, men in Arab headdresses brandishing automatic rifles as they did a victory dance around the aircraft. Hours later, Iraqi television showed two men it said made up the crew.

“We have a two-man crew missing,” confirmed Gen. Tommy Franks, the U.S. war commander. But he denied Iraqi reports that the craft had been shot down by farmers, and that two choppers had been lost.

Franks told reporters that 3,000 Iraqi prisoners had been taken. But he and other U.S. officials were more concerned with the fate of a handful of American POWs whose convoy was ambushed in the Iraqi desert over the weekend.

At the Pentagon, spokeswoman Torie Clark accused Iraqis of violating the rules of war by misusing white flags of surrender and other deceptions.

In London, the Ministry of Defense announced the first British combat death, a soldier who fell in fighting near Az Zubayr in southern Iraq, near the city of Basra.

Two other British troops were missing after their convoy was hit by continuing resistance in southern Iraq.

It was a fresh reminder that even in areas where American and British forces thought they had control, resistance continued to pop up.

“This is not a video game where everything is clear and neat and tidy,” said British spokesman Lt. Col. Ronnie McCourt. “Some enemy who feel that they want to carry on fighting will inevitably do so.”

Basra, Iraq’s second largest city, provided evidence of that, as Iraqis battled British forces on the outskirts of town. Commanders held off storming the city, hoping its Iraqi defenders would give up, but they have held firm.

The bombing in the north was carried out against a military barracks close to the line that separates Iraqi-held territory from the Kurdish-held region.

“People are evacuating, but not because of the bombing. They are afraid Saddam will respond with chemical weapons,” said Ahmad Qafoor, a school teacher.

There was no evidence of that — as yet.

But military commanders said American forces were still evaluating a plant captured by U.S. troops, and pursuing leads from captured Iraqis and documents in their search for weapons of mass destruction.

At the United Nations, Secretary General Kofi Annan warned of a humanitarian crisis in Basra and said “urgent measures” were needed to restore electricity and water supplies.