Longines Conquest Automatic 38mm L3.720.4.78.6

The Longines Conquest Automatic 38mm is the mid-size, time-and-date model in the Conquest line, which Longines fully revamped in 2023 and expanded in 2024. It uses a 38mm stainless steel case (10.9mm thick, 46.8mm lug-to-lug) with a screw-down crown and crown guards, 100m water resistance, a sunray dial with applied indexes and Super-LumiNova, and the automatic caliber L888.5 (silicon balance spring, 72-hour power reserve) on a brushed-and-polished H-link steel bracelet. Longines catalogues the 38mm automatic on bracelet in five sunray dials, each with its own reference suffix: green (L3.720.4.02.6), black (.52.6), gilt/champagne (.62.6), silver (.72.6) and blue (.92.6), plus rubber-strap versions. Note on the requested reference: the exact suffix L3.720.4.78.6 does not match any of Longines' listed 38mm automatic dials, and no authoritative Longines or retailer/database listing (WatchBase, Chrono24, PrestigeTime) for that exact reference could be located during research; the specs below are those shared across the entire L3.720.4 38mm automatic family, and the specific dial for the .78 suffix could not be verified.

The Conquest name is far older than the current watch. The Calibrated Wrist reports that the Conquest collection "has been a part of the Longines stable since 1954." Monochrome Watches likewise notes that it was "first introduced in 1954 (and the first to be trademarked over 70 years ago)," and is "among the longest lived" of the brand's collections.

Over the following decades the line was repositioned from a dress watch toward what The Calibrated Wrist describes as "the brand's flagship stainless steel sports watch." Monochrome Watches frames the current design as a clean-sheet effort: while "its name dates back to 1954," the modern Conquest was "fully revamped in 2023."

The 38mm automatic that this reference belongs to arrived in the 2024 expansion. Time and Watches documented the 2024 rollout across 30, 34 and 38mm cases, and reviewers including The Calibrated Wrist positioned the 38mm as filling the gap between the previously available 34mm and 41mm sizes.

The 38mm Conquest automatic runs the caliber L888.5. Monochrome Watches describes it as "exclusive to Longines, made by ETA (base 2892)," with 21 jewels and a 72-hour power reserve.

The movement beats at 25,200 vibrations per hour (3.5 Hz), per Time and Watches. The Calibrated Wrist identifies the defining change over the earlier L888 as a silicon balance spring, which it says "aids greatly in its magnetic resistance," alongside the same 25,200-vph frequency and 72-hour reserve. In other words, the "point five" designation marks an incremental upgrade — chiefly the silicon hairspring — rather than a new movement architecture.

The measured proportions are compact: Teddy Baldassarre's hands-on review lists a 38mm case that is 10.9mm thick with a 46.8mm lug-to-lug. The Calibrated Wrist adds a 19mm lug width, which it flags as an "odd ball" width that complicates aftermarket strap swaps.

Reviewing for Teddy Baldassarre, Mark Bernardo wrote that he was "surprised just how perfect the dimensions of the case looked and felt," and that the watch "slides easily under a shirt cuff." In Teddy Baldassarre's separate hands-on piece, Danny Milton observed that it "wears like a true 38mm" and that, despite the visually prominent crown, "you really don't notice it on the wrist," praising the bracelet's "solidity" as "a visual difference that separates it from the likes of, say, an Oyster style."

The Calibrated Wrist reached a similar conclusion, calling the watch "slender enough to wear with a cuff" and "a tasteful and classic design" that blends "vintage and modern cues." That reviewer singled out the champagne dial as "slightly more sophisticated" than the alternatives.

The 2024 Conquest range spans several sizes. Time and Watches documented new 30, 34 and 38mm models, while Monochrome Watches also covers the 41mm three-hander and a 42mm chronograph, the latter using the L898.5 caliber with a 59-hour power reserve.

For the 38mm automatic on bracelet, Longines catalogues five sunray dials, each with its own reference suffix: green (L3.720.4.02.6), black (.52.6), gilt/champagne (.62.6), silver (.72.6) and blue (.92.6). Monochrome Watches later added rubber-strap versions of the green, blue and black dials, which carry a .9 strap suffix (for example L3.720.4.02.9) and were introduced at EUR 2,200.

The requested reference in this record, L3.720.4.78.6, does not correspond to any of those catalogued 38mm automatic dials, and no Longines or retailer listing for that exact suffix could be located. Time and Watches notes that diamond-set and mother-of-pearl dial options exist in the smaller 30mm Conquest, but such treatments are not part of the 38mm automatic line.

Longines positioned the 38mm Conquest automatic on bracelet at a US launch MSRP of $2,075, per Teddy Baldassarre. The rubber-strap versions were introduced at EUR 2,200, per Monochrome Watches. The watch is sold through Longines boutiques and authorized dealers, and the five standard sunray-dial references are widely stocked.

A caution specific to this reference: as of research, the exact number L3.720.4.78.6 could not be found in any authorized-retailer or enthusiast-database catalog (Longines, WatchBase, Chrono24 and PrestigeTime), whereas its five sibling references are all listed. Anyone encountering L3.720.4.78.6 should verify it directly against Longines' current catalog before purchase; the numerically closest catalogued reference is the silver-dial L3.720.4.72.6.