转向军工是最好的出路

Turning to military industry is the best way out

Pure time travel without system, relying on IQ and knowledge to control the situation, don't enter if you don't like it.
The protagonist travels to a farm tractor family in the French Republic and becomes a quasi-rich third generation.
The only flaw is that it is near Paris, and the Germans will soon fight here. If you want to keep the family, you must save France.
Gallieni: "God, the enemy actually sent the flank to us!"
Xiafei: "There will be no such good thing, will this be a trap?"
The protagonist: "The dish is ready, you guys start, do it, and you still want me to send it to your mouth?"
...
The German army: "Is this a tractor factory? What the hell are these invulnerable steel monsters?"