Umadashi
Now rare, little understood and often overlooked devices - cornerstone in samurai castle defense and offense.
One of the weakest points of a castle and naturally the first to be targeted by enemies are the koguchi, entry and exit gates. Various efforts were made to protect the gates and one of the most effective defensive devices was known as an umadashi, written using the characters for horse 馬 and exit 出.
Often employed by the warlords of eastern Japan, and later adopted by the daimyo of the western provinces, Umadashi were a most effective style of defensive barrier and compound complex built directly in front of castle gates, just outside of the main moats, and used as a screen to allow cavalry charges and other attacks during times of siege. The Umadashi formed an obstacle for attacking enemy, preventing direct attack on the gates.