Oxygen tank explosion forced an abort. Crew used the LM as a lifeboat and returned safely.
Trajectory
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55 hours after launch, an oxygen tank in the Service Module exploded, crippling the spacecraft. Mission Control aborted the landing and shifted to a free-return trajectory using the Lunar Module Aquarius as a lifeboat, its descent engine performed two course corrections to bring the crew home. The free-return path took Apollo 13 around the far side of the Moon (the farthest humans had ever been from Earth: 400,171 km) before a successful Pacific splashdown.
1970 · 6 days 
JLJim LovellCommander
JSJack SwigertCommand Module Pilot
FHFred HaiseLunar Module Pilot