Has the us ever won a war in a foreign country while a republican president was in office?

The first Republican president was Abraham Lincoln. During his tenure, the Civil War was fought and won -- however, this was not a war in a foreign country.

Since Lincoln, we have fought several other wars.

The Spanish American war of 1898 was fought and won while Democratic president Grover Cleveland was in office.

Democrat Woodrow Wilson was in office when the United States and other Entente powers won World War I.

World War II was fought and won by two Democratic Presidents -- Franklin Roosevelt and Harry Truman.

The Korean War was fought under the tenure of Republican Dwight D. Eisenhower, but there is some dispute about whether that war was actually "won" and even if it is officially ended.

The Vietnam War was fought under the oversight of Presidents Eisenhower (R), Kennedy (D), Johnson (D), Nixon (R) and Ford (R). It is widely accepted that this is also not a conflict that the United States "won".

Now we come to perhaps your best bet of a Republican war that was "won" while the Republican was in office -- the first Persian Gulf War, fought during the administration of Republican George HW Bush.