A Marine staff sergeant (Aaron Eckhart) and his new platoon take on a mysterious and deadly enemy in Battle: Los Angeles.

Amid all the explosions, gun blasts, screaming, shouting, tears, fears and uproar that make up most of Battle: Los Angeles (opening March 11), you'll be pleased to know that the price of gasoline in August 2011 -- the date the action begins -- is $2.96. 

That's about the only note of cheer in this noisy ruckus between U.S. Marines and alien invaders, which spends about 22 seconds introducing characters, then jumps into the fray with guns blazing.

The 116-minute film stars Aaron Eckhart as noble Marine staff sergeant Michael Nantz, who, when meteors begin to splat into the Pacific Ocean, leads a small band of troops into what starts out as a just-in-case effort to evacuate Santa Monica and turns into an all-out war against hostile extraterrestrials.

Problem is, the last time Staff Sgt. Nantz led his troops into battle, he's the only one who got out alive. So there's some issues of trust going on, but they aren't explored with any depth. And the dialogue, when it can be understood over the din of rat-a-tat-tatting bullets, won't be winning any awards. If you want cues to what's going to happen next (not that it's hard to figure out), watch the actors' faces. 

Trust is the least of the soldiers' woes once somebody notices that in the center of each meteor shower is an object that appears to be mechanical -- "Not of this earth," grimly intones a military advisor. 

No kidding. The space dudes start shooting up, blowing up and frying up everything in sight, and it's up to Nantz and his green but game squad -- joined by a stray Air Force tech sergeant played by ever-tough Michelle Rodriguez, baring her teeth in every scene -- to put a stop to it.

Director Jonathan Liebesman employs juddering hand-held cameras that make you feel (somewhat queasily) that you are there. Explosions, like shout-outs between the troops, are right in your face, and some of the battle scenes between the good guys and the aliens (who look like gooey blobs with long froglike legs) show off well-done computer-generated effects for so long that they evolve from scary to exciting to, well, boring. 

The best way to look at Battle: Los Angeles, which traces its roots to a still unexplained occurrence in the city during World War II (see below), is as a summer movie that's arriving early. With the likes of Cars 2, X-Men: First Class, Green Lantern, Transformers: Dark of the Moon, Captain America: The First Avenger, and and Harry Potter and the Deathly Hallows: Part II, it can't hurt to get a head start on capturing audiences' hearts and minds. 

It's rated PG-13 for war violence, destruction and language. 

Background: The Battle of Los Angeles took place during the night between Feb. 24-25, 1942 during World War II. 

Beginning shortly after 2 a.m. Feb. 25 and continuing throughout the night, unidentified objects were reported over Los Angeles. The threat was so unusual that air raid sirens were sounded and a total blackout was ordered. At 3:16 a.m,. the 37th Coast Artillery Brigade began firing 12.8-pound antiaircraft shells at the objects. More than 1,400 shells were fired over the next 58 minutes as the objects moved south from Santa Monica to Long Beach.

"The obvious thought was that these were Japanese bombers come to attack the United States," says Bill Birnes, publisher of UFO magazine. "But it wasn't. They were flying too high. And the astounding thing was, not one artillery shell could hit the craft out of all the hundreds of shells that were fired. People outside that night swore that it was neither a plane nor a balloon -- it was a UFO. It floated, it glided. And to this day nobody can explain what that craft was, why our anti-aircraft guns couldn't hit it. It's a mystery that's never been resolved."

Descriptions of the UFOs varied widely. General George C. Marshall, in his initial memo to President Roosevelt regarding the event, wrote that the "unidentified airplanes ... [traveled at speeds ranging from] very slow to as much as 200 mph and from elevations of 9000 to 18,000 feet." (The memo may be viewed by clicking here.) 

The number of craft reported by observers ranged from 9 to 15 to 25.

At first, officials offered a very vague explanation. According to the Los Angeles Times (Feb. 26, 1942), secretary of the Navy Frank Knox dismissed the event as a "false alarm" due to "jittery nerves," but when this failed to satisfy the press and the public, the Army responded with a definitive answer that the craft and the battle were real, and the next day, Secretary of War Henry L. Stimson confirmed that.

Santa Monica's U.S. Representative Leland Ford was quoted in the Times on Feb. 27 calling for a Congressional investigation into the incident, but this went nowhere. In the years since, various explanations have been offered from Japanese planes to German craft launched from secret bases in Mexico to unidentified aircraft to weather balloons to sky lanterns to blimps.

However, it is also alleged that Gen. Marshall reported the Army had recovered an unidentified aircraft off the coast of California that indicated that the "mystery airplanes are in fact not earthly and according to secret intelligence sources they are in all probability of interplanetary origin."