Complex sentence: In 1867, during President Andrew Johnson's Administration, the Dominican government, under threat of Haitian invasion, had asked to be annexed by the United States, however, Congress was unwilling to comply to any proposal made by Johnson.
Split into simpler sentences: In 1867, during President Andrew Johnson's Administration, the Dominican government, under threat of Haitian invasion, had asked to be annexed by the United States. However, Congress was unwilling to comply to any proposal made by Johnson.