The Sentinel was a tank produced in small numbers in Australia. In common with the Wirraway fighter, it was built as a result of concern from the Australian government that the country could be cut off from both the UK and the USA and would be left to fend for itself against the Japanese.
Australia was basically trying to build an armaments industry from scratch with a very weak industrial base and one of the many issues was the lack of an adequate powerplant for the tank. The solution that was adopted was to link 3 110hp Cadillac engines together, although this was less than ideal.
The tank was further developed into the Thunderbolt and was starting to show some signs of progress but the availability of swarms of M3 and M4 medium tanks from the USA pretty much killed off the entire project. The Australian armored division for which these were destined was also never sent to war. With the focus of the Australian war effort shifting from the Middle East to the Pacific, the men were used as infantry replacements for the fighting in Indonesia.