Complex sentence: With government support, he was able to purchase more ships and increase Mitsubishi's shipping lines, which helped him drive two large foreign shipping companies out of the lucrative Shanghai route through the Mitsubishi Transportation Company which Yatarō founded.
Split into simpler sentences: With government support, he was able to purchase more ships and increase Mitsubishi's shipping lines. That helped him drive two large foreign shippers out of the lucrative Shanghai route through the Mitsubishi Transportation Company which Yatarō founded.