Nigerians marked their 42nd year of independence on Tuesday in a grim and fearful mood, as Africa's most populous nation stumbles on from one political crisis to the next. For thirty of its 42 years Nigeria was ruled by a series of brutal military dictators, each one vying to see who could plunder the greatest share of the nation's growing oil wealth. Hopes that civilian rule would bring better fortunes have proved to be short-lived.