Horii decided to raft down the river with a small party so he might more quickly reach the Buna -- Gona positions that were being threatened by the Australian advance .
The flooded river blocked the retreat of Horii 's force .
Horii decided to raft down the river with a small party so Horii might more quickly reach the Buna -- Gona positions that were being threatened by the Australian advance .
The flooded river blocked the retreat of Horii 's force .