First Battle of Rivas

First Battle of Rivas
	Part of the Filibuster War
Date	29 June 1855
Location	Rivas on the San Juan River, Nicaragua
Result	Democratic victory
Belligerents
Democratic Party; American filibusters;	Legitimist Party;
Commanders and leaders
Francisco Castellón; William Walker; Achilles Kewen †; Timothy Crocker †;	Manuel Arguëllo;
Strength
≈45 filibusters; ≈100 Nicaraguans (avoided action)	≈500–580 men
Casualties and losses
11 dead (6 men killed during combat, 5 wounded killed in the aftermath); 7 wounded	≈70 dead; +70 wounded

The First Battle of Rivas occurred on June 29, 1855, as part of the struggle to resist William Walker, an American filibuster, adventurer and mercenary who arrived in Nicaragua with a small army of mercenaries in June 1855 in support of the Democratic Party government of General Francisco Castellón in the Nicaraguan civil war. His army were defeated by the Legitimist Party.