How to achieve power: Before traveling back in time, learn old Chinese and a lot of history and philosophy. Bring with me technological designs from the future, particularly things expected to provide decisive strategic advantages to even small states (eg, gunpowder, Ming-era giant repeating cross bows, etc. Maybe some agricultural advances too). Find the local Mohists, teach them the relevant technologies and worldviews. Help them identify a state willing to listen to Mohists to prevent getting crushed, and slowly change the government from within while winning more and more wars.
Responding only to whether this part would work:
I like the idea of bringing back an entire sequence of war tech, so that you can always keep your side ahead of the curve.
I’m no historian of war, so the following might not be good enough, but something like...
Bring back horseback fighting techniques, which won out over chariot-based cavalry at some point. Teach this to the Mohists.
When others imitate, start teaching improved blacksmithing to the Mohists, for better swords, arrows, and armor.
When others imitate, bring out the gunpowder.
Etc.
Of course, this kind of sequence might require multiple generations, since any one of these technologies has the potential to continue providing momentum for a long time. But it seems like it could be incredibly effective.
Perhaps, if the Mohists are sane enough, you could teach them everything at once, but with the plan to carefully stage the use of various technologies.
Responding only to whether this part would work:
I like the idea of bringing back an entire sequence of war tech, so that you can always keep your side ahead of the curve.
I’m no historian of war, so the following might not be good enough, but something like...
Bring back horseback fighting techniques, which won out over chariot-based cavalry at some point. Teach this to the Mohists.
When others imitate, start teaching improved blacksmithing to the Mohists, for better swords, arrows, and armor.
When others imitate, bring out the gunpowder.
Etc.
Of course, this kind of sequence might require multiple generations, since any one of these technologies has the potential to continue providing momentum for a long time. But it seems like it could be incredibly effective.
Perhaps, if the Mohists are sane enough, you could teach them everything at once, but with the plan to carefully stage the use of various technologies.