Kaga joined Akagi as an aircraft carrier because Amagi could no longer take the second conversion slot. An earthquake damaged Amagi, so Kaga replaced it in the programme. The change connects the abandoned battlecruiser directly to the capital-ship hulls that survived in a new role. An external disaster therefore determined which Japanese ship became a carrier.
Notable Point · 15:06-15:30
Why Kaga replaced Amagi in the carrier conversions
Amagi's earthquake damage explains why Kaga joined Akagi as an aircraft carrier, linking the abandoned battlecruiser directly to Japan's later carrier force.