WI Shaka replaced the Zulu King Cetewayo in 1879?

[King Thomas]

As the Zulu War breaks out, an ASB reserects King Shaka, the first of the great Zulu kings, and puts him in charge of the 40,000+ Zulu Army that existed in 1879. In OTL the Zulu king of the time fought on the defensive, ordering his armies not to cross the Zululand border. Shaka, however would no doubt have been a very aggressive general. What happens next? Can Shaka force the British into retreat?

[Ghost 88]

As the Zulu War breaks out, an ASB reserects King Shaka, the first of the great Zulu kings, and puts him in charge of the 40,000+ Zulu Army that existed in 1879. In OTL the Zulu king of the time fought on the defensive, ordering his armies not to cross the Zululand border. Shaka, however would no doubt have been a very aggressive general. What happens next? Can Shaka force the British into retreat?
40K Zulus vs 10K Brits and Colonials with a Dozen Gattling Guns = Lots and lots and many many dead Zulus. In other words war over sooner.

[GiantMonkeyMan]

Chelmsford was an idiot who refused to believe that the zulu army was as large as it was and split his forces which was half composed of badly trained african tribesmen with a grudge against the zulu but little else keeping them in the fight... shaka could easily have crushed the three columns one after the other and taken their weapons. plus if the zulu don't give chelmsford the 2 months+ he had to regroup and head into natal they could have easily surprised the garrison and expanded zululand effectively... of course doing so would have prompted a heavier response from london and they may have eventually faced some decent troops for a change later on

of course, shaka kinda dismissed firearms as useless against large spear formations so he could be surprised by their effectiveness in the late 1800's but he was clever enough to allow reforms in the zulu army in the past so he might devise an effective way to incorperate firearms into his forces. he was also a pretty brutal ruler which could lead to more grudges from the people living in natal