Iraqis celebrated Christmas as an official holiday for the first time Thursday in one of the most peaceful days the country has seen since the US invaded nearly six years ago. But the day was not without violence. The US military said a soldier was killed in a rocket or mortar attack near the northern city of Mosul, and car bombs exploded in Baghdad and a city to the north, killing at least one person and wounding more than two dozen. Overall violence, however, is down sharply across the country. According to the US military, one year ago there were an average of 180 attacks a day, compared to just 10 a day now. Iraq's Christians - a small minority of a few hundred thousand in the overwhelmingly Muslim country of 26 million people - saluted a decision by the Shiite-led government to declare Christmas an official holiday. Many attended Mass in Baghdad and other cities and towns, mainly in the north where many fled to avoid violence.