Lock Horns

Drawn directly from nature. Stags, rams, and other horned animals genuinely fight head-to-head during mating season, interlocking their horns or antlers and pushing against each other in prolonged, often exhausting stand-offs, sometimes even becoming stuck together. The figurative phrase is an American one, first appearing in print in the early 19th century and turning up regularly in newspapers, local histories, and political writing by the 1830s-40s. One of the earliest documented examples is in The History of Virgil A. Stewart, compiled by H. R. Howard and published in New York in 1839.