One lion attacked another in an attempt to protect her cub.

From LiveLeak:

"We rounded a corner and saw mom walking with the one cub in her mouth, very quickly I noticed something was up as she was very nervous and kept running back to check on her other cub. Eventually we saw the young male watching her. She continued trying to move them but being naughty kids they were not co-operating. The male kept watching her every move and she kept watching him as he tried to move closer. She then had enough and smacked him silly next to the vehicle and started running back to her cubs, but half way there she decided he didn't get the message so she turned back. The male then crept under my car and she came smacked him a couple more times, shaking my car like it was jelly, and then ran to her babies. The male then slinked off in the opposite direction and mom managed to get the babies to a safe place. They are still alive and thriving (they are the ones seen on the north part of the H3 regularly). It was such an amazingly special thing to witness, the raw aggression and unbelievable love the mother had at the same time."